iv latin-american algorithms, graphs and optimization symposium - 2007
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IV Latin-American Algorithms, Graphs and Optimization Symposium - 2007. Puerto Varas - Chile. The Generalized Max-Controlled Set Problem. Carlos A. Martinhon Fluminense Fed. University Ivairton M. Santos - UFMT Luiz S. Ochi – IC/UFF. Contents. 1. Basic definitions. - PowerPoint PPT PresentationTRANSCRIPT
IV Latin-American Algorithms, Graphs and Optimization Symposium - 2007
Puerto Varas - Chile
The Generalized Max-Controlled The Generalized Max-Controlled Set ProblemSet Problem
Carlos A. MartinhonFluminense Fed. University
Ivairton M. Santos - UFMTLuiz S. Ochi – IC/UFF
2
ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
3
ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
4
Basic definitionsBasic definitions Consider G=(V,E) a non-oriented graph and
MV.
Definition: v is controlled by MV |NG[v]M| |NG[v]|/2
ExampleM
v1
v2
v3 v4
v5
v6 v7Cont(G,M)
5
Basic definitionsBasic definitions
• ContCont((G,MG,M) ) → set of vertices controlled by M→ set of vertices controlled by M..
• MM defines a defines a monopolymonopoly in in GG ContCont((G,MG,M) = ) = V.V.
0 1 2
3 4 5
M
Given G=(V,E) and MV:
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Basic definitionsBasic definitions Sandwich Graph
0 1 2
3 4 5
G1=(V,E1)
0 1 2
3 4 5
G=(V,E) where E1E E2
0 1 2
3 4 5
G2=(V,E2)
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Basic definitionsBasic definitions
Monopoly Verification Problem – MVP
• Given GGiven G11(V,E(V,E11), G), G22(V,E(V,E22) and M) and MV, V,
G=(V,E) s.t. E1 E E2 and M is monopoly nopoly in in GG ? ?
• Solved in polynomial time (Makino, Yamashita, Solved in polynomial time (Makino, Yamashita, Kameda, Kameda, AlgorithmicaAlgorithmica [2002]). [2002]).
8
Basic definitionsBasic definitions
- Max-Controlled Set Problem – MCSP• If the answer to the MVP is If the answer to the MVP is NO,NO, we have the we have the
MCSP!MCSP!
• In the MCSP, we hope to maximize the In the MCSP, we hope to maximize the
number of vertices controlled by M.number of vertices controlled by M.
• The MCSP is NP-hard !! (Makino The MCSP is NP-hard !! (Makino et alet al..
[2002]).[2002]).
9
3
Basic definitionsBasic definitions MCSP
0 1 2
5
4 6
M
Fixed EdgesOptional Edges
Not-controlled vertices
Controlled vertices
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ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
11
GMCSPGMCSP
f-controlled vertices
• A vertex A vertex iiVV is is -controlled by -controlled by MMV V iffiff, |, |
NNGG[[ii]]MM|-||-|NNGG[[ii]]UU| | i i , , withwith i i ZZ and and UU==V V \ \ M.M.
Vertices not -controlled by M-controlled vertices by M
0 1 2
3 4 5
M(0) (4) (1)
(3) (-2) (4)
f i fixed gaps (for i V)
12
GMCSPGMCSP
We also add positive weights
0 1
4 52 3
M
(0)[2] (0)[3]
(0)[5] (0)[7] (0)[10](0)[1]
Fixed EdgesOptional Edges
Vertices not -controlled-controlled vertices
13
GMCSPGMCSP
Generalized Max-Controlled Set Problem
• INPUT:INPUT: Given G Given G11(V,E(V,E11), G), G22(V,E(V,E22) and M) and MV V (with fixed gaps and positive weights).(with fixed gaps and positive weights).
• OBJECTIVE:OBJECTIVE: We want to find a sandwich We want to find a sandwich graph graph G=(V,E), in order to maximize the sum of the weights of all vertices f-controlled by M.
14
GMCSPGMCSP Reduction Rules:
We fix alloptional edges
We deleteall optional edges
M U=V\M
15
GMCSPGMCSP Reduction Rules
0 1 2
3 4 5
M(0)[1] (0)[1] (0)[1]
(0)[1] (0)[1] (0)[1]
E1D(M,M) E E1D(M,M)D(U,M)
Fixed EdgesOptional Edges
Vertices not -controlled-controlled vertices
16
GMCSPGMCSP Reduction Rules
• Consider the following partition of Consider the following partition of VV::
– MMACAC and and UUAC AC vertices always vertices always -controlled -controlled
– MMNCNC and and UUNC _NC _ vertices never vertices never -controlled -controlled
– MMRR and and UUR R vertices vertices -controlled or not.-controlled or not.
17
GMCSPGMCSP
Reduction Rules
MAC
MR
MNC
UAC
UR
UNC
M U
18
GMCSPGMCSP
Reduction Rules
MAC
MR
MNC
UAC
UR
UNC
M U
optional edges
fixed edges
19
PMCCGPMCCG Reduction Rules
0 1 2
3 4 5
M(0)[1] (0)[1] (0)[1]
(0)[1] (0)[1] (0)[1]
MSC={1}
UNC={5}
Fixed EdgesOptional Edges
Vertices not -controlled by M-controlled vertices by M
20
ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
21
GMCSPGMCSP ½-Approximation algorithm - GMCSP
• Algorithm 1Algorithm 1
1: 1: WW11 Summation of all weights for Summation of all weights for EE==EE11
2: 2: WW22 Summation of all weights for Summation of all weights for EE==EE22
3: 3: zzH1H1 maxmax{{WW11,,WW22}}
22
M(0)[5] (0)[1] (0)[3]
(0)[2] (0)[1] (0)[3]
GMCSPGMCSP
½-approximation for the GMCSP
Not -controlled vertices
f-controlled verticesFixed EdgesOptional Edges
0 1 2
3 4 5
W1=9
W2=7
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ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
24
GMCSPGMCSP LP formulation
• Consider Consider KK=|=|VV|+|+maxmax{|{|ii| s.t. | s.t. iiVV}}
Vi
ii zpz maxmax
VizK
fxaxa
iMj Uj
iijijijij
,1
Subject to:
1),(,1 Ejixij Vixii ,1
12 \),(},1,0{ EEjixij
Vizi },1,0{
P~
25
GMCSP GMCSP
• ConsiderConsider RRMj
iUj
ijijijiji UMifxaxab
,
M(2)
M
(1)
bi=3 bi=3
1),(,1 Ejixij
Vixii ,1
26
PMCCGPMCCG Stronger LP Formulation
Vi
ii zpz maxmax
RRii
Mj Ujiijijijij
UMizb
fxaxa
,1
Subject to:
1),(,1 Ejixij
Vixii ,1
12 \),(},1,0{ EEjixij
Vizi },1,0{
ACACi UMiz ,1
NCNCi UMiz ,0
P
27
Theorem Theorem : Let and the optimum : Let and the optimum
values of and respectively. Then:values of and respectively. Then:
GMCSPGMCSP
max~z
maxz
P~
P
maxmax~ zz
max~z
maxz
Z*=? Optimum objective value
What about the feasible solutions?
max
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GMCSPGMCSP
Theorem:Theorem: Consider a relaxed solution of Consider a relaxed solution of
with with .. and . and .
If for some (i,j)If for some (i,j)EE22, then there exists , then there exists
another relaxed solution withanother relaxed solution with
and and
),( zx P
2),(],1,0[ Ejixij Vizi ],1,0[
)1,0(ijx
)ˆ,ˆ( zx
2),(},1,0{ˆ Ejixij Vizi ],1,0[ˆ
29
PMCCGPMCCG Feasible solution based in the Linear
Relaxation
0 1 2
3 4
M
0,5
0,5
0,5
0,5
0 1 2
3 4
M
10
0
1
12 \),(,5,0 EEjixij 12 \),(},1,0{ˆ EEjixij
Fixed edgesOptional edges
Not-controlled vertices
Controlled vertices
30
Integer solution obtained from our stronger Linear Programming formulation.
• Algorithm 2Algorithm 2
– Given a relaxed solution for .Given a relaxed solution for .
– Define as Define as -controlled all vertice -controlled all vertice iiV V with with
, and not , and not -controlled if-controlled if . .
GMCSPGMCSP
),( zx P
1iz 1iz
31
Quality of upper and lower bounds
generated by our stronger formulation P
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ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
33
MCSPMCSP
• Combined HeuristicCombined Heuristic - CH- CH
• 1) 1) zz11 ½-approximation ½-approximation
• 2) 2) zz22 Based LP Heuristic Based LP Heuristic
• 3) z 3) z max{ max{zz11 , , zz22}}
((Martinhon&Protti, Martinhon&Protti, LNCCLNCC[2002]) [2002])
4,)1(2
1
2
1
nn
n
MCSP Similar combined heuristic with ratio:
34
ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. 4. Tabu Search ProcedureTabu Search Procedure
35
ContentsContents
1. Basic definitions1. Basic definitions
2. The Generalized Max-Controlled Set 2. The Generalized Max-Controlled Set ProblemProblem
3.3. a) A 1/2-Approximation procedurea) A 1/2-Approximation procedure
b) A Based LP Prog. Heuristicb) A Based LP Prog. Heuristic
c) A combined heuristicc) A combined heuristic
5. Comp. results and final comments 5. Comp. results and final comments
4. Tabu Search Procedure4. Tabu Search Procedure
36
Computational ResultsComputational Results Tabu Search solutions for instances with
50, 75 and 100 vertices.
37
THANK YOU !!
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GMCSPGMCSP Reduction Rules
• Rule 3Rule 3: Add to : Add to EE11 all edges of D( all edges of D(MMACACMMNCNC, U, URR).).
• Rule 4Rule 4: Remove from : Remove from EE22 the edges the edges
DD((MMRR,U,UACACUUNCNC).).
• Rule 5Rule 5: Add or remove at random the edges : Add or remove at random the edges
D(D(MMACACMMNCNC, U, UACACUUNCNC).).
MAC
MR
MNC
UAC
UR
UNC
M U
39
GMCSPGMCSP
Reduction Rules
• Given two graphs Given two graphs GG11 e e GG22, and 2 subsets , and 2 subsets A,BA,BVV, ,
we define: we define:
DD((A,BA,B)={()={(i,ji,j))EE22\\EE11 | | iiAA, , jjBB}}
• Rule 1Rule 1:: Add to Add to EE11 the edges the edges DD((M,MM,M).).
• Rule 2Rule 2:: Remove from Remove from EE22 the edges the edges DD((U,UU,U).).