We show that certain canonical realizations of the complexes Hom(G,H) and Hom+(G,H) of (partial) graph homomorphisms studied by Babson and Kozlov are in fact instances of the polyhedral Cayley trick. For G a complete graph, we then characterize when a canonical projection of these complexes is itself again a complex, and exhibit several well-known objects that arise as cells or subcomplexes of ...

A signed graph (G,?) is a G along with function ?:E(G)?{+,?}. closed walk of positive (resp., negative) if it has an even odd) number negative edges, counting repetitions. homomorphism (simple) to another vertex-mapping that preserves adjacencies and signs walks. The chromatic the minimum vertices |V(H)| (H,?) which admits homomorphism. Homomorphisms graphs have been attracting growing attentio...

For a symmetric bounded measurable function W on [0, 1] and a simple graph F , the homomorphism density

This paper focuses on the problem of multiplicative noise removal. We draw our inspiration from the modeling of speckle noise. By using a MAP estimator, we can derive a functional whose minimizer corresponds to the denoised image we want to recover. Although the functional is not convex, we prove the existence of a minimizer and we show the capability of our model on some numerical examples. We...

The paper addresses the problem of determining the Cramer–Rao lower bounds (CRLBs) for noise and change-point parameters, for steplike signals corrupted by multiplicative and/or additive white noise. Closed-form expressions for the signal and noise CRLBs are 5rst derived for an ideal step with a known change point. For an unknown change-point, the noise-free signal is modeled by a sigmoidal fun...

We study existence and uniqueness of a mild solution in the space of continuous functions and existence of an invariant measure for a class of reaction-diffusion systems on bounded domains of R , perturbed by a multiplicative noise. The reaction term is assumed to have polynomial growth and to be locally Lipschitz-continuous and monotone. The noise is white in space and time if d = 1 and colour...

In this paper, we establish the stability and superstability of J∗−derivations in J∗−algebras for the generalized Jensen–type functional equation rf( x+ y r ) + rf( x− y r ) = 2f(x). Finally, we investigate the stability of J∗−derivations by using the fixed point alternative.

...

Let Gn,k denote the Kneser graph whose vertices are the n-element subsets of a (2n + k)-element set and whose edges are the disjoint pairs. In this paper we prove that for any non-negative integer s there is no graph homomorphism from G4,2 to G4s+1,2s+1. This confirms a conjecture of Stahl in a special case.

The product homomorphism method is a combinatorial tool that can be used to develop polynomial PAC-learning algorithms in predicate logic. Using the product homomorphism method, we show that a single nonrecursive definite Horn clause is polynomially PAC-learnable if the background knowledge is a function-free extensional database over a single binary predicate and the ground atoms in the backgr...