Combinatorial optimization as polynomial eqns, Susan Margulies, UC Davis
Name wheel_6_1
Group JGD_Margulies
Matrix ID 2170
Num Rows 83
Num Cols 85
Nonzeros 254
Pattern Entries 254
Kind Combinatorial Problem
Symmetric No
Date 2008
Author S. Margulies
Editor J.-G. Dumas
Structural Rank 80
Structural Rank Full false
Num Dmperm Blocks 9
Strongly Connect Components 1
Num Explicit Zeros 0
Pattern Symmetry 0%
Numeric Symmetry 0%
Cholesky Candidate no
Positive Definite no
Type binary
SVD Statistics
Matrix Norm 3.582341e+00
Minimum Singular Value 6.719159e-17
Condition Number 5.331533e+16
Rank 72
sprank(A)-rank(A) 8
Null Space Dimension 11
Full Numerical Rank? no
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Combinatorial optimization as polynomial eqns, Susan Margulies, UC Davis
From Jean-Guillaume Dumas' Sparse Integer Matrix Collection,            
Expressing Combinatorial Optimization Problems by Systems of Polynomial 
Equations and the Nullstellensatz                                       
Authors: J.A. De Loera, J. Lee, Susan Margulies, S. Onn                 
(Submitted on 5 Jun 2007)                                               
Abstract: Systems of polynomial equations over the complex or real      
numbers can be used to model combinatorial problems. In this way, a     
combinatorial problem is feasible (e.g. a graph is 3-colorable,         
hamiltonian, etc.) if and only if a related system of polynomial        
equations has a solution. In the first part of this paper, we construct 
new polynomial encodings for the problems of finding in a graph its     
longest cycle, the largest planar subgraph, the edge-chromatic number,  
or the largest k-colorable subgraph.  For an infeasible polynomial      
system, the (complex) Hilbert Nullstellensatz gives a certificate that  
the associated combinatorial problem is infeasible. Thus, unless P =    
NP, there must exist an infinite sequence of infeasible instances of    
each hard combinatorial problem for which the minimum degree of a       
Hilbert Nullstellensatz certificate of the associated polynomial system 
grows.  We show that the minimum-degree of a Nullstellensatz            
certificate for the non-existence of a stable set of size greater than  
the stability number of the graph is the stability number of the graph. 
Moreover, such a certificate contains at least one term per stable set  
of G. In contrast, for non-3- colorability, we found only graphs with   
Nullstellensatz certificates of degree four.                            
Filename in JGD collection: Margulies/wheel_6_1.sms