A Conditional Information Inequality and Its Combinatorial Applications

Autor: Nikolai K. Vereshchagin, Andrei Romashchenko, Tarik Kaced
Přispěvatelé: Systèmes complexes, automates et pavages (ESCAPE), Laboratoire d'Informatique de Robotique et de Microélectronique de Montpellier (LIRMM), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM), Department of Mathematical Logic and Theory of Algorithms, Lomonosov Moscow State University (MSU)
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Zdroj: IEEE Transactions on Information Theory
IEEE Transactions on Information Theory, Institute of Electrical and Electronics Engineers, 2018, 64 (5), pp.3610-3615. ⟨10.1109/TIT.2018.2806486⟩
ISSN: 0018-9448
Popis: We show that the inequality $H(A | B,X) + H(A | B,Y) \leqslant H(A | B)$ for jointly distributed random variables $A,B,X,Y$ , which does not hold in general case, holds under some natural condition on the support of the probability distribution of $A,B,X,Y$ . This result generalizes a version of the conditional Ingleton inequality: if for some distribution $I(X \mskip 5mu {:} \mskip 5mu Y | A) = H(A | X,Y)=0$ , then $I(A \mskip 5mu {:} \mskip 5mu B) \leqslant I(A \mskip 5mu {:} \mskip 5mu B | X) + I(A \mskip 5mu {:} \mskip 5mu B | Y) + I(X \mskip 5mu {:} \mskip 5mu Y)$ . We present two applications of our result. The first one is the following easy-to-formulate theorem on edge colorings of bipartite graphs: assume that the edges of a bipartite graph are colored in $K$ colors so that each two edges sharing a vertex have different colors and for each pair (left vertex $x$ , right vertex $y$ ) there is at most one color $a$ such both $x$ and $y$ are incident to edges with color $a$ ; assume further that the degree of each left vertex is at least $L$ and the degree of each right vertex is at least $R$ . Then $K \geqslant LR$ . The second application is a new method to prove lower bounds for biclique cover of bipartite graphs.
Databáze: OpenAIRE