Linear complementarity problem: Difference between revisions

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<math>\left[\begin{array}{c}{x}\\ {\mu}\end{array}\right] = \left[\begin{array}{cc} {Q} & {A}_{eq}^{T}\\ -{A}_{eq} & {0}\end{array}\right]^{-1} \left[\begin{array}{c} {A}^{T}{\lambda}-{c}\\-{b}_{eq}\end{array}\right] \,</math>

In fact, most QP solvers work on the LCP formulation, including the [[interior point method]], principal / complementarity pivoting, and [[active set]] methods.<ref name="Murty88">{{harvtxt|Murty|1988}}</ref><ref name="CPS92">{{harvtxt|Cottle|Pang|Stone|1992}}</ref> LCP problems can be solved also by the [[criss-cross algorithm]],<ref>{{harvtxt|Fukuda|Namiki|1994}}</ref><ref>{{harvtxt|Fukuda|Terlaky|1997}}</ref><ref name="HRT">{{cite journal|first1=D. |last1=den&nbsp;Hertog|first2=C.|last2=Roos|first3=T.|last3=Terlaky|title=The linear complementarity problem, sufficient matrices, and the criss-cross method|journal=Linear Algebra and its Applications|volume=187|date=1 July 1993|pages=1–14|url=http://core.ac.uk/download/pdf/6714737.pdf|doi=10.1016/0024-3795(93)90124-7|url=http://www.sciencedirect.com/science/article/pii/0024379593901247|<!-- ref=harv -->|url=http://arno.uvt.nl/show.cgi?fid=72943|format=pdf}}</ref><ref name="CIsufficient">{{cite journal|first1=Zsolt|last1=Csizmadia|first2=Tibor|last2=Illés|title=New criss-cross type algorithms for linear complementarity problems with sufficient matrices|journal=Optimization Methods and Software|volume=21|year=2006|number=2|pages=247–266|doi=10.1080/10556780500095009|

url=http://www.cs.elte.hu/opres/orr/download/ORR03_1.pdf|format=pdf|<!-- ref=harv -->}}</ref> conversely, for linear complementarity problems, the criss-cross algorithm terminates finitely only if the matrix is a sufficient matrix.<ref name="HRT"/><ref name="CIsufficient"/> A [[sufficient&nbsp;matrix]] is a generalization both of a [[positive-definite matrix]] and of a [[P-matrix]], whose [[principal&nbsp;minor]]s are each positive.<ref name="HRT"/><ref name="CIsufficient"/><ref>{{cite journal|last1=Cottle|first1=R.&nbsp;W.|authorlink1=Richard W. Cottle|last2=Pang|first2=J.-S.|last3=Venkateswaran|first3=V.|title=Sufficient matrices and the linear&nbsp;complementarity problem|journal=Linear Algebra and its Applications|volume=114–115|date=March–April 1989|pages=231–249|doi=10.1016/0024-3795(89)90463-1|url=http://www.sciencedirect.com/science/article/pii/0024379589904631|mr=986877|ref=harv}}</ref>

Such LCPs can be solved when they are formulated abstractly using [[oriented matroid|oriented-matroid]] theory.<ref name="Todd" >{{harvtxt|Todd|1985|}}</ref><ref>{{harvtxt|Terlaky|Zhang|1993}}: {{cite journal|last1=Terlaky|first1=Tamás|<!-- authorlink1=Tamás Terlaky -->|last2=Zhang|first2=Shu&nbsp;Zhong|title=Pivot rules for linear programming: A Survey on recent theoretical developments|issue=Degeneracy in optimization problems|journal=Annals of Operations Research|volume=46–47|year=1993|issue=1|pages=203–233|doi=10.1007/BF02096264|mr=1260019|id= {{citeseerx|10.1.1.36.7658}} |publisher=Springer Netherlands|issn=0254-5330|ref=harv}}</ref><ref>{{cite book|last=Björner|first=Anders|last2=Las&nbsp;Vergnas|author2-link=Michel Las Vergnas|first2=Michel|last3=Sturmfels|first3=Bernd|authorlink3=Bernd Sturmfels|last4=White|first4=Neil|last5=Ziegler|first5=Günter|authorlink5=Günter M. Ziegler|title=Oriented Matroids|chapter=10 Linear programming|publisher=Cambridge University Press|year=1999|isbn=978-0-521-77750-6|url=http://ebooks.cambridge.org/ebook.jsf?bid=CBO9780511586507|pages=417–479|doi=10.1017/CBO9780511586507|MR=1744046}}</ref>