Hyperbolic set covering problems with competing ground-set elements
|
|
- Tiffany Stone
- 6 years ago
- Views:
Transcription
1 g Hyperbolic set covering problems with competing ground-set elements Edoardo Amaldi, Sandro Bosio and Federico Malucelli Dipartimento di Elettronica e Informazione (DEI), Politecnico di Milano, Italy XI Workshop on Combinatorial Optimization, Aussois, 2007.
2 Outline g Problems definition The motivating application: Wireless Local Area Network design Hyperbolic integer programming formulation Complexity and Approximability results Linearizations and Lagrangean Relaxation Ongoing work and concluding remarks
3 Set Covering notation g
4 Set Covering notation g I I: a finite groundset
5 Set Covering notation g J I: a finite groundset J : a collection of subsets J = {I j I : j J}
6 Set Covering notation g i J i I: a finite groundset J : a collection of subsets J = {I j I : j J} J i J : subcollection of the subsets covering an element i I
7 Set Covering notation g S I: a finite groundset J : a collection of subsets J = {I j I : j J} J i J : cover S: subcollection of the subsets covering an element i I a subcollection indexed by S J such that j S I j = I
8 Set Covering problems g Classical Set Covering Problem (SCP): Given an instance (I, J ) and a cost c j R for each j J,
9 Set Covering problems g Classical Set Covering Problem (SCP): Given an instance (I, J ) and a cost c j R for each j J, find a cover S that minimizes the total cost c(s) = c j j S
10 Set Covering problems g Classical Set Covering Problem (SCP): Given an instance (I, J ) and a cost c j R for each j J, find a cover S that minimizes the total cost c(s) = c j j S Variants: Set Partitioning forbidden overlap Set Multicover required overlap
11 Set Covering problems g Classical Set Covering Problem (SCP): Given an instance (I, J ) and a cost c j R for each j J, find a cover S that minimizes the total cost c(s) = c j j S Variants: Set Partitioning forbidden overlap Set Multicover required overlap Also: Quadratic objective functions Maximum coverage...
12 Coverage share g Given a covering instance (I, J ), a cover S and an element i I coverage share: r(s, i) = + N i (S)
13 Coverage share g Given a covering instance (I, J ), a cover S and an element i I coverage share: r(s, i) = + N i (S) S
14 Coverage share g Given a covering instance (I, J ), a cover S and an element i I coverage share: r(s, i) = + N i (S) N i i r(s,i)= 3
15 Coverage share g Given a covering instance (I, J ), a cover S and an element i I coverage share: r(s, i) = + N i (S) i r(s,i)= 7 N i
16 Coverage share g Given a covering instance (I, J ), a cover S and an element i I coverage share: r(s, i) = + N i (S) i r(s,i)= 7 Fraction of resource received by i assuming fair allocation N i among the competing elements (neighbors of i)
17 Coverage share problems g Maximum Total Coverage Share Problem (TCSP): Given an instance (I, J ), find a cover S that maximizes f t (S) = i I + N i (S)
18 Coverage share problems g Maximum Total Coverage Share Problem (TCSP): Given an instance (I, J ), find a cover S that maximizes f t (S) = i I + N i (S) Maximum Minimum Coverage Share Problem (MCSP): Given an instance (I, J ), find a cover S that maximizes f m (S) = min i I + N i (S)
19 Coverage share problems g Maximum Total Coverage Share Problem (TCSP): Given an instance (I, J ), find a cover S that maximizes f t (S) = i I + N i (S) Maximum Minimum Coverage Share Problem (MCSP): Given an instance (I, J ), find a cover S that maximizes f m (S) = min i I + N i (S) Set covering problems with competing ground-set elements
20 Coverage share problems g
21 Coverage share problems g Instance
22 Coverage share problems g Instance SCP opt S = 2 f t (S) =.40 f m (S) =
23 Coverage share problems g Instance SCP opt TCSP opt S = 2 f t (S) =.40 f m (S) = S = 4 f t (S) = 3.64 f m (S) = 7
24 Coverage share problems g Instance SCP opt TCSP opt MCSP opt S = 2 f t (S) =.40 f m (S) = S = 4 f t (S) = 3.64 f m (S) = 7 S = 4 f t (S) = 3.42 f m (S) = 4
25 Coverage share problems g Instance SCP opt TCSP opt MCSP opt S = 2 f t (S) =.40 f m (S) = S = 4 f t (S) = 3.64 f m (S) = 7 S = 4 f t (S) = 3.42 f m (S) = 4 Privilege covers whose subsets have small cardinality and limited overlaps.
26 Wireless Local Area Network g IEEE 802. WLAN: a set of Access Points each able of serving a set of users
27 Wireless Local Area Network g IEEE 802. WLAN: a set of Access Points each able of serving a set of users WLANs are becoming pervasive in airports, trains and train stations, private companies, universities, hotels,...
28 Wireless Local Area Network g IEEE 802. WLAN: a set of Access Points each able of serving a set of users Medium Access Control (MAC) Protocol: A user can access the network if and only if no other user is interfering directly or indirectly
29 Wireless Local Area Network g IEEE 802. WLAN: a set of Access Points each able of serving a set of users Medium Access Control (MAC) Protocol: A user can access the network if and only if no other user is interfering directly or indirectly Assuming uniform peak traffic and fair access after collision, coverage share of element i fraction of time used by user i
30 Wireless Local Area Network g IEEE 802. WLAN: a set of Access Points each able of serving a set of users Due to protocol issues, increasing sizes of deployed WLANs and limited resources, and optimization models and methods can be very useful to support the planning decisions.
31 Previous and related work g WLAN design: Large-scale WLAN design (Hills 0,...) Max average signal quality in test points (Rodrigues, Mateus and Loureiro 00/0) Max coverage level (Kamenetsky and Unbehaun 02) Max capacity based on constraint satisfaction (Prommak et al. 02)... First hyperbolic model and heuristics (Amaldi, Capone, Cesana and Malucelli 04)
32 Integer programming formulations g max i I + N i (S) ( TCSP ) s.t. I j = I complete coverage j S S J select subcollection
33 Integer programming formulations g max i I + N i (S) ( TCSP ) s.t. I j = I complete coverage j S S J select subcollection Variables: x j = if subset I j is selected (0 otherwise) y ih = if elements i and h are neighbors (0 otherwise)
34 Integer programming formulations g max ( TCSP ) s.t. i I + j J i x j y ih x j y ih x j {0, } h N i y ih j J i J h x j y ih {0, } i I i I, h N i, j J i J h i I, h N i j J i I, h N i
35 Integer programming formulations g max ( TCSP ) s.t. i I + j J i x j h N i y ih 0- hyperbolic sum problem i I y ih x j y ih j J i J h x j x j {0, } y ih {0, } i I, h N i, j J i J h i I, h N i j J i I, h N i
36 Integer programming formulations g (MCSP) max s.t. min i I + j J i x j h N i y ih i I y ih x j y ih j J i J h x j i I, h N i, j J i J h i I, h N i x j {0, } j J y ih {0, } i I, h N i
37 Integer programming formulations g (MCSP) max s.t. min i I + j J i x j h N i y ih = i I + min max i I h N i y ih y ih x j y ih j J i J h x j x j {0, } y ih {0, } i I, h N i, j J i J h i I, h N i j J i I, h N i
38 Connection with Quadratic SCP g Quadratic Set Covering Problem (QSCP): Given (I, J ), Q = {q jl R : j, l J} (wlog symmetric with zero diagonal) and c = {c j R : j J}, find a cover S J that maximizes q(s) = 2 j S l S q jl + j S c j
39 Connection with Quadratic SCP g Quadratic Set Covering Problem (QSCP): Given (I, J ), Q = {q jl R : j, l J} (wlog symmetric with zero diagonal) and c = {c j R : j J}, find a cover S J that maximizes q(s) = 2 j S l S q jl + j S c j Choice: c j = i I j I j q jl = i I j I l ( I j I l I j I l ) (for j l)
40 Connection with Quadratic SCP g Quadratic Set Covering Problem (QSCP): Given (I, J ), Q = {q jl R : j, l J} (wlog symmetric with zero diagonal) and c = {c j R : j J}, find a cover S J that maximizes q(s) = 2 j S l S q jl + j S c j Choice: c j = i I j I j q jl = i I j I l ( I j I l I j I l ) (for j l) Then we can verify that: f t (S) = q(s) if at most two subsets overlap f t (S) q(s) otherwise (overhestimated penalty)
41 Previous and related work g Unconstrained 0- Hyperbolic Programming Single-ratio: NP-hard, poly with positive denominator (Hammer and Rudeanu 68) Multiple-ratio: NP-hard; tackled by SA, Tabu, and decomposing into independent polynomial single-ratio problems (Hansen, Poggi de Aragao and Ribeiro 90/9) Constrained 0- Hyperbolic Programming Single-ratio (Stancu-Minasian 97) Multiple-ratio: MILP convex reformulations (Tawarmalani, Ahmed and Sahinidis 02) Quadratic Set Covering Problem Various application oriented works (Bazaara 75, Boros, Hammer et al. 00,...) Generic: not 2 p( I ) -approximable for any polynomial p() (Escoffier and Convex: approximable within O(ln 2 ( I )) but not within ρ ln 2 ( I ) Hammer 05)
42 Complexity and Approximability (TCSP) g
43 Complexity and Approximability (TCSP) g Generic instances
44 Complexity and Approximability (TCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Not approximable within ρ ( I ) ε or ρ ( J ) ε for a given ρ > 0 and any ε > 0, unless NP = ZPP Reduction from Max Independent Set
45 Complexity and Approximability (TCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Not approximable within ρ ( I ) ε or ρ ( J ) ε for a given ρ > 0 and any ε > 0, unless NP = ZPP Reduction from Max Independent Set Euclidean 2D Instances
46 Complexity and Approximability (TCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Not approximable within ρ ( I ) ε or ρ ( J ) ε for a given ρ > 0 and any ε > 0, unless NP = ZPP Reduction from Max Independent Set Euclidean 2D Instances Strongly NP-hard (does not admit a FPTAS unless P = NP) Adapting and extending a reduction for Disc-Cover (Fowler et al. 8) Under a reasonable restriction, admits a PTAS Using the shifting lemma
47 Complexity and Approximability (TCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Not approximable within ρ ( I ) ε or ρ ( J ) ε for a given ρ > 0 and any ε > 0, unless NP = ZPP Reduction from Max Independent Set Euclidean 2D Instances Strongly NP-hard (does not admit a FPTAS unless P = NP) Adapting and extending a reduction for Disc-Cover (Fowler et al. 8) Under a reasonable restriction, admits a PTAS Using the shifting lemma Euclidean D Instances (or instances with CC covering matrix)
48 Complexity and Approximability (TCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Not approximable within ρ ( I ) ε or ρ ( J ) ε for a given ρ > 0 and any ε > 0, unless NP = ZPP Reduction from Max Independent Set Euclidean 2D Instances Strongly NP-hard (does not admit a FPTAS unless P = NP) Adapting and extending a reduction for Disc-Cover (Fowler et al. 8) Under a reasonable restriction, admits a PTAS Using the shifting lemma Euclidean D Instances (or instances with CC covering matrix) Polynomial-time solvable Longest path on an appropriate directed acyclic digraph
49 Complexity and Approximability (MCSP) g
50 Complexity and Approximability (MCSP) g Generic instances
51 Complexity and Approximability (MCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Polynomial-time solvable if I j = 2 Reduction to perfect b-matching
52 Complexity and Approximability (MCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Polynomial-time solvable if I j = 2 Reduction to perfect b-matching Euclidean 2D Instances
53 Complexity and Approximability (MCSP) g Generic instances Strongly NP-hard (Amaldi et al. 04) Polynomial-time solvable if I j = 2 Reduction to perfect b-matching Euclidean 2D Instances Strongly NP-hard (does not admit a FPTAS unless P = NP) Adapting the reduction for TCSP Not approximable within 3/2 unless P = NP Consequence of the above reduction Under a reasonable restriction, approximable within a factor 3 Tiling with hexagons
54 Linearization g For each ratio + is introduced a variable r i 0 and the quadratic constraint y ih h i r i = + r i + y ih h i h i r i y ih =
55 Linearization g For each ratio + is introduced a variable r i 0 and the quadratic constraint y ih h i r i = + r i + y ih h i h i r i y ih = r i y ih is standardly linearized with a variable z ih 0 and the constraints z ih u i y ih z ih l i y ih z ih r i + u i (y ih ) z ih r i + l i (y ih )
56 Linearization g For each ratio + is introduced a variable r i 0 and the quadratic constraint y ih h i r i = + r i + y ih h i h i r i y ih = r i y ih is standardly linearized with a variable z ih 0 and the constraints z ih u i y ih z ih l i y ih z ih r i + u i (y ih ) z ih r i + l i (y ih ) NB: r i is continuous and bounded, and y is binary
57 Tightening linearization of bilinear terms g z y Z = {(r, y, z) : z = r y, r [l, u], y {0, }} { } z ly, z r + u(y ), conv(z) = z uy, z r + l(y ) 0 l u r
58 Tightening linearization of bilinear terms g z y Z = {(r, y, z) : z = r y, r [l, u], y {0, }} { } z ly, z r + u(y ), conv(z) = z uy, z r + l(y ) 0 l u r Z = {(r, y, z) : z = 0, r [l, u ], y = 0} Z = {(r, y, z) : z = r, r [l, u ], y = }
59 Tightening linearization of bilinear terms g z y Z = {(r, y, z) : z = r y, r [l, u], y {0, }} { } z ly, z r + u(y ), conv(z) = z uy, z r + l(y ) 0 l u r Z = {(r, y, z) : z = 0, r [l 0, u 0 ], y = 0} Z = {(r, y, z) : z = r, r [l, u ], y = }
60 Tightening linearization of bilinear terms g z y Z = {(r, y, z) : z = r y, r [l, u], y {0, }} { } z ly, z r + u(y ), conv(z) = z uy, z r + l(y ) 0 l Z = {(r, y, z) : z = 0, r [l 0, u 0 ], y = 0} Z = {(r, y, z) : z = r, r [l, u ], y = } { z l y, z r + u 0 (y ), } 0 z u r y conv(z ) = z u y, z r + l 0 (y ) l 0 l u 0 u r
61 Lagrangean relaxation g By applying Lagragean relaxation to an appropriate reformulation the problem is decomposed into smaller and easier subproblems.
62 Lagrangean relaxation g By applying Lagragean relaxation to an appropriate reformulation the problem is decomposed into smaller and easier subproblems. Expanded formulation obtained by adding for each i I a vector χ i = {χ ij : j J i } of binary variables, one for each covering subset. Incidence vector of a local covering solution for i.
63 Lagrangean relaxation g By applying Lagragean relaxation to an appropriate reformulation the problem is decomposed into smaller and easier subproblems. Expanded formulation obtained by adding for each i I a vector χ i = {χ ij : j J i } of binary variables, one for each covering subset. Incidence vector of a local covering solution for i. J i i
64 Lagrangean relaxation g By applying Lagragean relaxation to an appropriate reformulation the problem is decomposed into smaller and easier subproblems. Expanded formulation obtained by adding for each i I a vector χ i = {χ ij : j J i } of binary variables, one for each covering subset. Incidence vector of a local covering solution for i. i
65 Lagrangean relaxation g Expanded formulation: max s.t. X i I X + P h N i y ih j J i x j i I ( y ih x j i I, h N i, j J i J h (2 X χ ij i I (3 j J i y ih χ ij i I, h N i, j J i J h (4 X y ih χ ij i I, h N i (5 j J i J h x j = χ ij i I, j J i (6 y ih = y hi i I, h N i : h > i (7 x j, χ ij, y ih {0,} Several possibilities, depending on which constraints are deleted/dualized
66 Lagrangean relaxation g Expanded formulation: max s.t. X i I X + P h N i y ih j J i x j i I ( y ih x j i I, h N i, j J i J h (2 X χ ij i I (3 j J i y ih χ ij i I, h N i, j J i J h (4 X y ih χ ij i I, h N i (5 j J i J h x j = χ ij i I, j J i (6 y ih = y hi i I, h N i : h > i (7 x j, χ ij, y ih {0,} Several possibilities, depending on which constraints are deleted/dualized
67 Lagrangean relaxation g Expanded formulation: max s.t. X i I X + P h N i y ih j J i x j i I ( y ih x j i I, h N i, j J i J h (2 X χ ij i I (3 j J i y ih χ ij i I, h N i, j J i J h (4 X y ih χ ij i I, h N i (5 j J i J h x j = χ ij i I, j J i (6 y ih = y hi i I, h N i : h > i (7 x j, χ ij, y ih {0,} Without (2), (6) and (7): one SCP and I independent hyperbolic subproblems
68 Lagrangean relaxation g Expanded formulation: max s.t. X i I X + P h N i y ih j J i x j i I ( y ih x j i I, h N i, j J i J h (2 X χ ij i I (3 j J i y ih χ ij i I, h N i, j J i J h (4 X y ih χ ij i I, h N i (5 j J i J h x j = χ ij i I, j J i (6 y ih = y hi i I, h N i : h > i (7 x j, χ ij, y ih {0,} LAG a : remove (2) and dualize (6) and (7) NP-hard hyperbolic subproblems
69 Lagrangean relaxation g Expanded formulation: max s.t. X i I X + P h N i y ih j J i x j i I ( y ih x j i I, h N i, j J i J h (2 X χ ij i I (3 j J i y ih χ ij i I, h N i, j J i J h (4 X y ih χ ij i I, h N i (5 j J i J h x j = χ ij i I, j J i (6 y ih = y hi i I, h N i : h > i (7 x j, χ ij, y ih {0,} LAG b : remove (5), (6) and dualize (2), (7) polynomial hyperbolic subproblems
70 Lagrangean subproblem for LAG b g Problem for a given element i: max s.t. + P + y h h N i X χ j j J i X h N i c h y h y h χ j χ j {0,} y h {0,} h N i, j J i J h j J i h N i
71 Lagrangean subproblem for LAG b g Problem for a given element i: max s.t. + P + y h h N i X χ j j J i X h N i c h y h y h χ j χ j {0,} y h {0,} h N i, j J i J h j J i h N i
72 Lagrangean subproblem for LAG b g Fix one variable χ l to (try all). This covers all h I l. max s.t. + P + y h h N i X χ j j J i X h N i c h y h y h χ j χ j {0,} y h {0,} h N i, j J i J h j J i h N i
73 Lagrangean subproblem for LAG b g Fix one variable χ l to (try all). This covers all h I l. max + P h N i y h + s.t. χ l = X h N i c h y h y h χ j χ j {0,} y h {0,} h N i, j J i J h j J i h N i
74 Lagrangean subproblem for LAG b g Fix one variable χ l to (try all). This covers all h I l. max + P h N i y h + s.t. χ l = y h = X h N i c h y h h I l y h χ j χ j {0,} y h {0,} h N i \ I l, j J i J h j J i h N i
75 Lagrangean subproblem for LAG b g Fix all other χ j to 0 (no o.f. contribution). max + P h N i y h + s.t. χ l = y h = X h N i c h y h h I l y h χ j χ j {0,} y h {0,} h N i \ I l, j J i J h j J i h N i
76 Lagrangean subproblem for LAG b g Fix all other χ j to 0 (no o.f. contribution). max + P h N i y h + s.t. y h = y h {0,} X h N i c h y h h I l h N i
77 Lagrangean subproblem for LAG b g Remains an unconstrained problem with hyperbolic+linear o.f.. max + P h N i y h + s.t. y h = y h {0,} X h N i c h y h h I l h N i
78 Lagrangean subproblem for LAG b g Remains an unconstrained problem with hyperbolic+linear o.f.. max + P h N i y h + s.t. y h = y h {0,} X h N i c h y h h I l h N i Since hyperbolic depends only on how many and not on which:
79 Lagrangean subproblem for LAG b g Remains an unconstrained problem with hyperbolic+linear o.f.. max + P h N i y h + s.t. y h = y h {0,} X h N i c h y h h I l h N i Since hyperbolic depends only on how many and not on which: ) sort c h coefficients in nonincreasing order. f
80 Lagrangean subproblem for LAG b g Remains an unconstrained problem with hyperbolic+linear o.f.. max + P h N i y h + s.t. y h = y h {0,} X h N i c h y h h I l h N i Since hyperbolic depends only on how many and not on which: ) sort c h coefficients in nonincreasing order. f 2) fix the first k variables to, the remaining to 0 (try all k).
81 Comparison - our department g Our Department
82 Comparison - our department g Our Department TCSP best solution Standard Linearization Improved Linearization LAG b J I den gap time gap time gap time (%) (sec) (%) (sec) (%) (sec) : time limit exceeded
83 Comparison - our department g Our Department TCSP best solution SCP optimal solution
84 Comparison - our department g Our Department TCSP best solution SCP optimal solution Tests with a WLAN simulator (ns-2): 2.58 Mb/s for SCP solution, 5.8 Mb/s for TCSP solution
85 Comparison - synthetic instances g Standard Linearization Improved Linearization LAG b J I den gap stdev time stdev gap stdev time stdev gap stdev time stdev GEOMETRIC INSTANCES (LOW DENSITY) GEOMETRIC INSTANCES (HIGH DENSITY) STANDARD SCP INSTANCES (CLASS SCP4*) STANDARD SCP INSTANCES (CLASS SCPE*) : the primal-dual gap is zero (proven optimality) : time limit exceeded for all instances of the class
86 Concluding remarks g This presentation:
87 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements
88 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions
89 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation
90 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work:
91 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work: Linearization by Dantzig-Wolfe decomposition
92 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work: Linearization by Dantzig-Wolfe decomposition Refined hyperbolic models, accounting for relevant features of WLANs
93 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work: Linearization by Dantzig-Wolfe decomposition Refined hyperbolic models, accounting for relevant features of WLANs Direct interference and node association
94 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work: Linearization by Dantzig-Wolfe decomposition Refined hyperbolic models, accounting for relevant features of WLANs Direct interference and node association Multiple frequencies and adaptive rate
95 Concluding remarks g This presentation: New interesting class: set covering problems with competing ground-set elements Complexity and approximability for generic and geometric versions Improved linearization and efficient Lagrangean relaxation Ongoing work: Linearization by Dantzig-Wolfe decomposition Refined hyperbolic models, accounting for relevant features of WLANs Direct interference and node association Multiple frequencies and adaptive rate
Linköping University Post Print. Solving Nonlinear Covering Problems Arising in WLAN Design
Linköping University Post Print Solving Nonlinear Covering Problems Arising in WLAN Design Edoardo Amaldi, Sandro Bosio, Federico Malucelli and Di Yuan N.B.: When citing this work, cite the original article.
More informationPlanning maximum capacity Wireless Local Area Networks
Edoardo Amaldi Sandro Bosio Antonio Capone Matteo Cesana Federico Malucelli Di Yuan Planning maximum capacity Wireless Local Area Networks http://www.elet.polimi.it/upload/malucell Outline Application
More informationChapter 3: Discrete Optimization Integer Programming
Chapter 3: Discrete Optimization Integer Programming Edoardo Amaldi DEIB Politecnico di Milano edoardo.amaldi@polimi.it Website: http://home.deib.polimi.it/amaldi/opt-16-17.shtml Academic year 2016-17
More informationChapter 3: Discrete Optimization Integer Programming
Chapter 3: Discrete Optimization Integer Programming Edoardo Amaldi DEIB Politecnico di Milano edoardo.amaldi@polimi.it Sito web: http://home.deib.polimi.it/amaldi/ott-13-14.shtml A.A. 2013-14 Edoardo
More information3.4 Relaxations and bounds
3.4 Relaxations and bounds Consider a generic Discrete Optimization problem z = min{c(x) : x X} with an optimal solution x X. In general, the algorithms generate not only a decreasing sequence of upper
More informationKnapsack. Bag/knapsack of integer capacity B n items item i has size s i and profit/weight w i
Knapsack Bag/knapsack of integer capacity B n items item i has size s i and profit/weight w i Goal: find a subset of items of maximum profit such that the item subset fits in the bag Knapsack X: item set
More informationLecture 11 October 7, 2013
CS 4: Advanced Algorithms Fall 03 Prof. Jelani Nelson Lecture October 7, 03 Scribe: David Ding Overview In the last lecture we talked about set cover: Sets S,..., S m {,..., n}. S has cost c S. Goal: Cover
More informationCS675: Convex and Combinatorial Optimization Fall 2016 Combinatorial Problems as Linear and Convex Programs. Instructor: Shaddin Dughmi
CS675: Convex and Combinatorial Optimization Fall 2016 Combinatorial Problems as Linear and Convex Programs Instructor: Shaddin Dughmi Outline 1 Introduction 2 Shortest Path 3 Algorithms for Single-Source
More informationWeighted Acyclic Di-Graph Partitioning by Balanced Disjoint Paths
Weighted Acyclic Di-Graph Partitioning by Balanced Disjoint Paths H. Murat AFSAR Olivier BRIANT Murat.Afsar@g-scop.inpg.fr Olivier.Briant@g-scop.inpg.fr G-SCOP Laboratory Grenoble Institute of Technology
More informationChapter 11. Approximation Algorithms. Slides by Kevin Wayne Pearson-Addison Wesley. All rights reserved.
Chapter 11 Approximation Algorithms Slides by Kevin Wayne. Copyright @ 2005 Pearson-Addison Wesley. All rights reserved. 1 Approximation Algorithms Q. Suppose I need to solve an NP-hard problem. What should
More informationwhere X is the feasible region, i.e., the set of the feasible solutions.
3.5 Branch and Bound Consider a generic Discrete Optimization problem (P) z = max{c(x) : x X }, where X is the feasible region, i.e., the set of the feasible solutions. Branch and Bound is a general semi-enumerative
More information3.10 Lagrangian relaxation
3.10 Lagrangian relaxation Consider a generic ILP problem min {c t x : Ax b, Dx d, x Z n } with integer coefficients. Suppose Dx d are the complicating constraints. Often the linear relaxation and the
More informationOutline. Relaxation. Outline DMP204 SCHEDULING, TIMETABLING AND ROUTING. 1. Lagrangian Relaxation. Lecture 12 Single Machine Models, Column Generation
Outline DMP204 SCHEDULING, TIMETABLING AND ROUTING 1. Lagrangian Relaxation Lecture 12 Single Machine Models, Column Generation 2. Dantzig-Wolfe Decomposition Dantzig-Wolfe Decomposition Delayed Column
More informationOn the Complexity of Budgeted Maximum Path Coverage on Trees
On the Complexity of Budgeted Maximum Path Coverage on Trees H.-C. Wirth An instance of the budgeted maximum coverage problem is given by a set of weighted ground elements and a cost weighted family of
More information4y Springer NONLINEAR INTEGER PROGRAMMING
NONLINEAR INTEGER PROGRAMMING DUAN LI Department of Systems Engineering and Engineering Management The Chinese University of Hong Kong Shatin, N. T. Hong Kong XIAOLING SUN Department of Mathematics Shanghai
More informationCS675: Convex and Combinatorial Optimization Fall 2014 Combinatorial Problems as Linear Programs. Instructor: Shaddin Dughmi
CS675: Convex and Combinatorial Optimization Fall 2014 Combinatorial Problems as Linear Programs Instructor: Shaddin Dughmi Outline 1 Introduction 2 Shortest Path 3 Algorithms for Single-Source Shortest
More informationApproximation Basics
Approximation Basics, Concepts, and Examples Xiaofeng Gao Department of Computer Science and Engineering Shanghai Jiao Tong University, P.R.China Fall 2012 Special thanks is given to Dr. Guoqiang Li for
More informationDecomposition Methods for Quadratic Zero-One Programming
Decomposition Methods for Quadratic Zero-One Programming Borzou Rostami This dissertation is submitted for the degree of Doctor of Philosophy in Information Technology Advisor: Prof. Federico Malucelli
More informationChapter 11. Approximation Algorithms. Slides by Kevin Wayne Pearson-Addison Wesley. All rights reserved.
Chapter 11 Approximation Algorithms Slides by Kevin Wayne. Copyright @ 2005 Pearson-Addison Wesley. All rights reserved. 1 P and NP P: The family of problems that can be solved quickly in polynomial time.
More informationBBM402-Lecture 20: LP Duality
BBM402-Lecture 20: LP Duality Lecturer: Lale Özkahya Resources for the presentation: https://courses.engr.illinois.edu/cs473/fa2016/lectures.html An easy LP? which is compact form for max cx subject to
More informationThe Knapsack Problem. 28. April /44
The Knapsack Problem 20 10 15 20 W n items with weight w i N and profit p i N Choose a subset x of items Capacity constraint i x w i W wlog assume i w i > W, i : w i < W Maximize profit i x p i 28. April
More informationELE539A: Optimization of Communication Systems Lecture 16: Pareto Optimization and Nonconvex Optimization
ELE539A: Optimization of Communication Systems Lecture 16: Pareto Optimization and Nonconvex Optimization Professor M. Chiang Electrical Engineering Department, Princeton University March 16, 2007 Lecture
More informationDual fitting approximation for Set Cover, and Primal Dual approximation for Set Cover
duality 1 Dual fitting approximation for Set Cover, and Primal Dual approximation for Set Cover Guy Kortsarz duality 2 The set cover problem with uniform costs Input: A universe U and a collection of subsets
More informationRecoverable Robust Knapsacks: Γ -Scenarios
Recoverable Robust Knapsacks: Γ -Scenarios Christina Büsing, Arie M. C. A. Koster, and Manuel Kutschka Abstract In this paper, we investigate the recoverable robust knapsack problem, where the uncertainty
More informationCSE541 Class 22. Jeremy Buhler. November 22, Today: how to generalize some well-known approximation results
CSE541 Class 22 Jeremy Buhler November 22, 2016 Today: how to generalize some well-known approximation results 1 Intuition: Behavior of Functions Consider a real-valued function gz) on integers or reals).
More informationMVE165/MMG631 Linear and integer optimization with applications Lecture 8 Discrete optimization: theory and algorithms
MVE165/MMG631 Linear and integer optimization with applications Lecture 8 Discrete optimization: theory and algorithms Ann-Brith Strömberg 2017 04 07 Lecture 8 Linear and integer optimization with applications
More informationNotes on Dantzig-Wolfe decomposition and column generation
Notes on Dantzig-Wolfe decomposition and column generation Mette Gamst November 11, 2010 1 Introduction This note introduces an exact solution method for mathematical programming problems. The method is
More informationLecture 9: Dantzig-Wolfe Decomposition
Lecture 9: Dantzig-Wolfe Decomposition (3 units) Outline Dantzig-Wolfe decomposition Column generation algorithm Relation to Lagrangian dual Branch-and-price method Generated assignment problem and multi-commodity
More informationA Lagrangian relaxation method for solving choice-based mixed linear optimization models that integrate supply and demand interactions
A Lagrangian relaxation method for solving choice-based mixed linear optimization models that integrate supply and demand interactions Meritxell Pacheco Shadi Sharif Azadeh, Michel Bierlaire, Bernard Gendron
More informationExtended Formulations, Lagrangian Relaxation, & Column Generation: tackling large scale applications
Extended Formulations, Lagrangian Relaxation, & Column Generation: tackling large scale applications François Vanderbeck University of Bordeaux INRIA Bordeaux-Sud-Ouest part : Defining Extended Formulations
More informationOn the Complexity of the Minimum Independent Set Partition Problem
On the Complexity of the Minimum Independent Set Partition Problem T-H. Hubert Chan 1, Charalampos Papamanthou 2, and Zhichao Zhao 1 1 Department of Computer Science the University of Hong Kong {hubert,zczhao}@cs.hku.hk
More informationSubmodular and Linear Maximization with Knapsack Constraints. Ariel Kulik
Submodular and Linear Maximization with Knapsack Constraints Ariel Kulik Submodular and Linear Maximization with Knapsack Constraints Research Thesis Submitted in partial fulfillment of the requirements
More informationmaxz = 3x 1 +4x 2 2x 1 +x 2 6 2x 1 +3x 2 9 x 1,x 2
ex-5.-5. Foundations of Operations Research Prof. E. Amaldi 5. Branch-and-Bound Given the integer linear program maxz = x +x x +x 6 x +x 9 x,x integer solve it via the Branch-and-Bound method (solving
More informationInteger program reformulation for robust branch-and-cut-and-price
Integer program reformulation for robust branch-and-cut-and-price Marcus Poggi de Aragão Informática PUC-Rio Eduardo Uchoa Engenharia de Produção Universidade Federal Fluminense Outline of the talk Robust
More informationWelfare Maximization with Friends-of-Friends Network Externalities
Welfare Maximization with Friends-of-Friends Network Externalities Extended version of a talk at STACS 2015, Munich Wolfgang Dvořák 1 joint work with: Sayan Bhattacharya 2, Monika Henzinger 1, Martin Starnberger
More informationApproximation Algorithms for Maximum. Coverage and Max Cut with Given Sizes of. Parts? A. A. Ageev and M. I. Sviridenko
Approximation Algorithms for Maximum Coverage and Max Cut with Given Sizes of Parts? A. A. Ageev and M. I. Sviridenko Sobolev Institute of Mathematics pr. Koptyuga 4, 630090, Novosibirsk, Russia fageev,svirg@math.nsc.ru
More informationHeuristics and Upper Bounds for a Pooling Problem with Cubic Constraints
Heuristics and Upper Bounds for a Pooling Problem with Cubic Constraints Matthew J. Real, Shabbir Ahmed, Helder Inàcio and Kevin Norwood School of Chemical & Biomolecular Engineering 311 Ferst Drive, N.W.
More informationImproved dynamic programming and approximation results for the Knapsack Problem with Setups
Improved dynamic programming and approximation results for the napsack Problem with Setups Ulrich Pferschy Rosario Scatamacchia Abstract We consider the 0 1 napsack Problem with Setups (PS). Items are
More informationACO Comprehensive Exam March 17 and 18, Computability, Complexity and Algorithms
1. Computability, Complexity and Algorithms (a) Let G(V, E) be an undirected unweighted graph. Let C V be a vertex cover of G. Argue that V \ C is an independent set of G. (b) Minimum cardinality vertex
More information- Well-characterized problems, min-max relations, approximate certificates. - LP problems in the standard form, primal and dual linear programs
LP-Duality ( Approximation Algorithms by V. Vazirani, Chapter 12) - Well-characterized problems, min-max relations, approximate certificates - LP problems in the standard form, primal and dual linear programs
More informationApproximation complexity of min-max (regret) versions of shortest path, spanning tree, and knapsack
Approximation complexity of min-max (regret) versions of shortest path, spanning tree, and knapsack Hassene Aissi, Cristina Bazgan, and Daniel Vanderpooten LAMSADE, Université Paris-Dauphine, France {aissi,bazgan,vdp}@lamsade.dauphine.fr
More information3.10 Column generation method
3.10 Column generation method Many relevant decision-making problems can be formulated as ILP problems with a very large (exponential) number of variables. Examples: cutting stock, crew scheduling, vehicle
More informationLecture 15 (Oct 6): LP Duality
CMPUT 675: Approximation Algorithms Fall 2014 Lecturer: Zachary Friggstad Lecture 15 (Oct 6): LP Duality Scribe: Zachary Friggstad 15.1 Introduction by Example Given a linear program and a feasible solution
More informationSolving Mixed-Integer Nonlinear Programs
Solving Mixed-Integer Nonlinear Programs (with SCIP) Ambros M. Gleixner Zuse Institute Berlin MATHEON Berlin Mathematical School 5th Porto Meeting on Mathematics for Industry, April 10 11, 2014, Porto
More informationLecture 7: Lagrangian Relaxation and Duality Theory
Lecture 7: Lagrangian Relaxation and Duality Theory (3 units) Outline Lagrangian dual for linear IP Lagrangian dual for general IP Dual Search Lagrangian decomposition 1 / 23 Joseph Louis Lagrange Joseph
More informationCS599: Convex and Combinatorial Optimization Fall 2013 Lecture 17: Combinatorial Problems as Linear Programs III. Instructor: Shaddin Dughmi
CS599: Convex and Combinatorial Optimization Fall 2013 Lecture 17: Combinatorial Problems as Linear Programs III Instructor: Shaddin Dughmi Announcements Today: Spanning Trees and Flows Flexibility awarded
More informationTHE TRAVELING SALESMAN PROBLEM (TSP) is one
Proceedings of the 2013 Federated Conference on Computer Science and Information Systems pp. 377 384 Quadratic TSP: A lower bounding procedure and a column generation approach Borzou Rostami, Federico
More informationDecomposition-based Methods for Large-scale Discrete Optimization p.1
Decomposition-based Methods for Large-scale Discrete Optimization Matthew V Galati Ted K Ralphs Department of Industrial and Systems Engineering Lehigh University, Bethlehem, PA, USA Départment de Mathématiques
More informationOn the complexity of maximizing the minimum Shannon capacity in wireless networks by joint channel assignment and power allocation
On the complexity of maximizing the minimum Shannon capacity in wireless networks by joint channel assignment and power allocation Mikael Fallgren Royal Institute of Technology December, 2009 Abstract
More informationClassification of Dantzig-Wolfe Reformulations for MIP s
Classification of Dantzig-Wolfe Reformulations for MIP s Raf Jans Rotterdam School of Management HEC Montreal Workshop on Column Generation Aussois, June 2008 Outline and Motivation Dantzig-Wolfe reformulation
More informationInteger Linear Programming Modeling
DM554/DM545 Linear and Lecture 9 Integer Linear Programming Marco Chiarandini Department of Mathematics & Computer Science University of Southern Denmark Outline 1. 2. Assignment Problem Knapsack Problem
More informationThe Maximum Flow Problem with Disjunctive Constraints
The Maximum Flow Problem with Disjunctive Constraints Ulrich Pferschy Joachim Schauer Abstract We study the maximum flow problem subject to binary disjunctive constraints in a directed graph: A negative
More informationLimitations of Algorithm Power
Limitations of Algorithm Power Objectives We now move into the third and final major theme for this course. 1. Tools for analyzing algorithms. 2. Design strategies for designing algorithms. 3. Identifying
More information3.10 Column generation method
3.10 Column generation method Many relevant decision-making (discrete optimization) problems can be formulated as ILP problems with a very large (exponential) number of variables. Examples: cutting stock,
More informationScenario Grouping and Decomposition Algorithms for Chance-constrained Programs
Scenario Grouping and Decomposition Algorithms for Chance-constrained Programs Siqian Shen Dept. of Industrial and Operations Engineering University of Michigan Joint work with Yan Deng (UMich, Google)
More informationOn Two Class-Constrained Versions of the Multiple Knapsack Problem
On Two Class-Constrained Versions of the Multiple Knapsack Problem Hadas Shachnai Tami Tamir Department of Computer Science The Technion, Haifa 32000, Israel Abstract We study two variants of the classic
More informationarxiv: v1 [math.oc] 3 Jan 2019
The Product Knapsack Problem: Approximation and Complexity arxiv:1901.00695v1 [math.oc] 3 Jan 2019 Ulrich Pferschy a, Joachim Schauer a, Clemens Thielen b a Department of Statistics and Operations Research,
More informationInteger Programming ISE 418. Lecture 16. Dr. Ted Ralphs
Integer Programming ISE 418 Lecture 16 Dr. Ted Ralphs ISE 418 Lecture 16 1 Reading for This Lecture Wolsey, Chapters 10 and 11 Nemhauser and Wolsey Sections II.3.1, II.3.6, II.3.7, II.5.4 CCZ Chapter 8
More informationThe maximum edge-disjoint paths problem in complete graphs
Theoretical Computer Science 399 (2008) 128 140 www.elsevier.com/locate/tcs The maximum edge-disjoint paths problem in complete graphs Adrian Kosowski Department of Algorithms and System Modeling, Gdańsk
More informationFaster Algorithms for some Optimization Problems on Collinear Points
Faster Algorithms for some Optimization Problems on Collinear Points Ahmad Biniaz Prosenjit Bose Paz Carmi Anil Maheshwari J. Ian Munro Michiel Smid June 29, 2018 Abstract We propose faster algorithms
More informationInterpretable Nonnegative Matrix Decompositions
27 August 2008 Outline 1 Introduction 2 Definitions 3 Algorithms and Complexity 4 Experiments Synthetic Data Real Data 5 Conclusions Outline 1 Introduction 2 Definitions 3 Algorithms and Complexity 4 Experiments
More information1 Solution of a Large-Scale Traveling-Salesman Problem... 7 George B. Dantzig, Delbert R. Fulkerson, and Selmer M. Johnson
Part I The Early Years 1 Solution of a Large-Scale Traveling-Salesman Problem............ 7 George B. Dantzig, Delbert R. Fulkerson, and Selmer M. Johnson 2 The Hungarian Method for the Assignment Problem..............
More informationCombinatorial optimization problems
Combinatorial optimization problems Heuristic Algorithms Giovanni Righini University of Milan Department of Computer Science (Crema) Optimization In general an optimization problem can be formulated as:
More informationIntegrating advanced discrete choice models in mixed integer linear optimization
Integrating advanced discrete choice models in mixed integer linear optimization Meritxell Pacheco Shadi Sharif Azadeh, Michel Bierlaire, Bernard Gendron Transport and Mobility Laboratory (TRANSP-OR) École
More informationOptimal matching in wireless sensor networks
Optimal matching in wireless sensor networks A. Roumy, D. Gesbert INRIA-IRISA, Rennes, France. Institute Eurecom, Sophia Antipolis, France. Abstract We investigate the design of a wireless sensor network
More informationOPTIMIZATION. joint course with. Ottimizzazione Discreta and Complementi di R.O. Edoardo Amaldi. DEIB Politecnico di Milano
OPTIMIZATION joint course with Ottimizzazione Discreta and Complementi di R.O. Edoardo Amaldi DEIB Politecnico di Milano edoardo.amaldi@polimi.it Website: http://home.deib.polimi.it/amaldi/opt-15-16.shtml
More informationPolyhedral Results for A Class of Cardinality Constrained Submodular Minimization Problems
Polyhedral Results for A Class of Cardinality Constrained Submodular Minimization Problems Shabbir Ahmed and Jiajin Yu Georgia Institute of Technology A Motivating Problem [n]: Set of candidate investment
More informationInterference in Cellular Networks: The Minimum Membership Set Cover Problem
Interference in Cellular Networks: The Minimum Membership Set Cover Problem Fabian Kuhn 1, Pascal von Rickenbach 1, Roger Wattenhofer 1, Emo Welzl 2, and Aaron Zollinger 1 kuhn@tikeeethzch, pascalv@tikeeethzch,
More information5 Integer Linear Programming (ILP) E. Amaldi Foundations of Operations Research Politecnico di Milano 1
5 Integer Linear Programming (ILP) E. Amaldi Foundations of Operations Research Politecnico di Milano 1 Definition: An Integer Linear Programming problem is an optimization problem of the form (ILP) min
More informationConvexification of Mixed-Integer Quadratically Constrained Quadratic Programs
Convexification of Mixed-Integer Quadratically Constrained Quadratic Programs Laura Galli 1 Adam N. Letchford 2 Lancaster, April 2011 1 DEIS, University of Bologna, Italy 2 Department of Management Science,
More informationDuality of LPs and Applications
Lecture 6 Duality of LPs and Applications Last lecture we introduced duality of linear programs. We saw how to form duals, and proved both the weak and strong duality theorems. In this lecture we will
More informationEECS 495: Combinatorial Optimization Lecture Manolis, Nima Mechanism Design with Rounding
EECS 495: Combinatorial Optimization Lecture Manolis, Nima Mechanism Design with Rounding Motivation Make a social choice that (approximately) maximizes the social welfare subject to the economic constraints
More informationP,NP, NP-Hard and NP-Complete
P,NP, NP-Hard and NP-Complete We can categorize the problem space into two parts Solvable Problems Unsolvable problems 7/11/2011 1 Halting Problem Given a description of a program and a finite input, decide
More informationDiscrete Optimization 2010 Lecture 10 P, N P, and N PCompleteness
Discrete Optimization 2010 Lecture 10 P, N P, and N PCompleteness Marc Uetz University of Twente m.uetz@utwente.nl Lecture 9: sheet 1 / 31 Marc Uetz Discrete Optimization Outline 1 N P and co-n P 2 N P-completeness
More informationMultiuser Downlink Beamforming: Rank-Constrained SDP
Multiuser Downlink Beamforming: Rank-Constrained SDP Daniel P. Palomar Hong Kong University of Science and Technology (HKUST) ELEC5470 - Convex Optimization Fall 2018-19, HKUST, Hong Kong Outline of Lecture
More informationAn 0.5-Approximation Algorithm for MAX DICUT with Given Sizes of Parts
An 0.5-Approximation Algorithm for MAX DICUT with Given Sizes of Parts Alexander Ageev Refael Hassin Maxim Sviridenko Abstract Given a directed graph G and an edge weight function w : E(G) R +, themaximumdirectedcutproblem(max
More informationOn the Tightness of an LP Relaxation for Rational Optimization and its Applications
OPERATIONS RESEARCH Vol. 00, No. 0, Xxxxx 0000, pp. 000 000 issn 0030-364X eissn 526-5463 00 0000 000 INFORMS doi 0.287/xxxx.0000.0000 c 0000 INFORMS Authors are encouraged to submit new papers to INFORMS
More informationScheduling Parallel Jobs with Linear Speedup
Scheduling Parallel Jobs with Linear Speedup Alexander Grigoriev and Marc Uetz Maastricht University, Quantitative Economics, P.O.Box 616, 6200 MD Maastricht, The Netherlands. Email: {a.grigoriev, m.uetz}@ke.unimaas.nl
More informationNP-Completeness. f(n) \ n n sec sec sec. n sec 24.3 sec 5.2 mins. 2 n sec 17.9 mins 35.
NP-Completeness Reference: Computers and Intractability: A Guide to the Theory of NP-Completeness by Garey and Johnson, W.H. Freeman and Company, 1979. NP-Completeness 1 General Problems, Input Size and
More information12. LOCAL SEARCH. gradient descent Metropolis algorithm Hopfield neural networks maximum cut Nash equilibria
12. LOCAL SEARCH gradient descent Metropolis algorithm Hopfield neural networks maximum cut Nash equilibria Lecture slides by Kevin Wayne Copyright 2005 Pearson-Addison Wesley h ttp://www.cs.princeton.edu/~wayne/kleinberg-tardos
More informationCS 6901 (Applied Algorithms) Lecture 3
CS 6901 (Applied Algorithms) Lecture 3 Antonina Kolokolova September 16, 2014 1 Representative problems: brief overview In this lecture we will look at several problems which, although look somewhat similar
More informationCombinatorial Auction: A Survey (Part I)
Combinatorial Auction: A Survey (Part I) Sven de Vries Rakesh V. Vohra IJOC, 15(3): 284-309, 2003 Presented by James Lee on May 10, 2006 for course Comp 670O, Spring 2006, HKUST COMP670O Course Presentation
More information0-1 Reformulations of the Network Loading Problem
0-1 Reformulations of the Network Loading Problem Antonio Frangioni 1 frangio@di.unipi.it Bernard Gendron 2 bernard@crt.umontreal.ca 1 Dipartimento di Informatica Università di Pisa Via Buonarroti, 2 56127
More informationOptimization Exercise Set n. 4 :
Optimization Exercise Set n. 4 : Prepared by S. Coniglio and E. Amaldi translated by O. Jabali 2018/2019 1 4.1 Airport location In air transportation, usually there is not a direct connection between every
More informationOn Approximating Minimum 3-connected m-dominating Set Problem in Unit Disk Graph
1 On Approximating Minimum 3-connected m-dominating Set Problem in Unit Disk Graph Bei Liu, Wei Wang, Donghyun Kim, Senior Member, IEEE, Deying Li, Jingyi Wang, Alade O. Tokuta, Member, IEEE, Yaolin Jiang
More informationNonlinear Discrete Optimization
Nonlinear Discrete Optimization Technion Israel Institute of Technology http://ie.technion.ac.il/~onn Billerafest 2008 - conference in honor of Lou Billera's 65th birthday (Update on Lecture Series given
More informationOptimization Exercise Set n.5 :
Optimization Exercise Set n.5 : Prepared by S. Coniglio translated by O. Jabali 2016/2017 1 5.1 Airport location In air transportation, usually there is not a direct connection between every pair of airports.
More informationLinear-Time Approximation Algorithms for Unit Disk Graphs
Linear-Time Approximation Algorithms for Unit Disk Graphs Guilherme D. da Fonseca Vinícius G. Pereira de Sá elina M. H. de Figueiredo Universidade Federal do Rio de Janeiro, Brazil Abstract Numerous approximation
More informationMulticommodity Flows and Column Generation
Lecture Notes Multicommodity Flows and Column Generation Marc Pfetsch Zuse Institute Berlin pfetsch@zib.de last change: 2/8/2006 Technische Universität Berlin Fakultät II, Institut für Mathematik WS 2006/07
More informationl p -Norm Constrained Quadratic Programming: Conic Approximation Methods
OUTLINE l p -Norm Constrained Quadratic Programming: Conic Approximation Methods Wenxun Xing Department of Mathematical Sciences Tsinghua University, Beijing Email: wxing@math.tsinghua.edu.cn OUTLINE OUTLINE
More informationMVE165/MMG630, Applied Optimization Lecture 6 Integer linear programming: models and applications; complexity. Ann-Brith Strömberg
MVE165/MMG630, Integer linear programming: models and applications; complexity Ann-Brith Strömberg 2011 04 01 Modelling with integer variables (Ch. 13.1) Variables Linear programming (LP) uses continuous
More informationInteger Equal Flows. 1 Introduction. Carol A. Meyers Andreas S. Schulz
Integer Equal Flows Carol A Meyers Andreas S Schulz Abstract We examine an NP-hard generalization of the network flow problem known as the integer equal flow problem The setup is the same as a standard
More informationPart 4. Decomposition Algorithms
In the name of God Part 4. 4.4. Column Generation for the Constrained Shortest Path Problem Spring 2010 Instructor: Dr. Masoud Yaghini Constrained Shortest Path Problem Constrained Shortest Path Problem
More informationDecomposition Methods for Integer Programming
Decomposition Methods for Integer Programming J.M. Valério de Carvalho vc@dps.uminho.pt Departamento de Produção e Sistemas Escola de Engenharia, Universidade do Minho Portugal PhD Course Programa Doutoral
More informationRobust Combinatorial Optimization under Budgeted-Ellipsoidal Uncertainty
EURO Journal on Computational Optimization manuscript No. (will be inserted by the editor) Robust Combinatorial Optimization under Budgeted-Ellipsoidal Uncertainty Jannis Kurtz Received: date / Accepted:
More informationInformation in Aloha Networks
Achieving Proportional Fairness using Local Information in Aloha Networks Koushik Kar, Saswati Sarkar, Leandros Tassiulas Abstract We address the problem of attaining proportionally fair rates using Aloha
More informationAll-norm Approximation Algorithms
All-norm Approximation Algorithms Yossi Azar Leah Epstein Yossi Richter Gerhard J. Woeginger Abstract A major drawback in optimization problems and in particular in scheduling problems is that for every
More informationNP Completeness and Approximation Algorithms
Chapter 10 NP Completeness and Approximation Algorithms Let C() be a class of problems defined by some property. We are interested in characterizing the hardest problems in the class, so that if we can
More informationOn the hardness of losing width
On the hardness of losing width Marek Cygan 1, Daniel Lokshtanov 2, Marcin Pilipczuk 1, Micha l Pilipczuk 1, and Saket Saurabh 3 1 Institute of Informatics, University of Warsaw, Poland {cygan@,malcin@,mp248287@students}mimuwedupl
More informationAlgorithms. Outline! Approximation Algorithms. The class APX. The intelligence behind the hardware. ! Based on
6117CIT - Adv Topics in Computing Sci at Nathan 1 Algorithms The intelligence behind the hardware Outline! Approximation Algorithms The class APX! Some complexity classes, like PTAS and FPTAS! Illustration
More information