The 2-Disjoint Connected Subgraphs problem asks if a given graph has two vertex-disjoint connected subgraphs containing prespecified sets of vertices. We show that this problem is NP-complete even if one of the sets has cardinality 2. The Longest Path Contractibility problem asks for the largest integer ` for which an input graph can be contracted to the path P` on ` vertices. We show that the ...

anticipated; electricity will recall the contractibility,and often, when you have brought, back normal contractibility, you find that the paralysis is cured. The interrupted galvanic current and faradisation will both answer ; if galvanisation is employed, the sponge-handles, well-wetted, should be used, and each set of muscles taken in turn. An interesting case of extensive paralysis, with los...

Modifying a given graph to obtain another graph is a wellstudied problem with applications in many fields. Given two input graphs G and H, the Contractibility problem is to decide whether H can be obtained from G by a sequence of edge contractions. This problem is known to be NP-complete already when both input graphs are trees of bounded diameter. We prove that Contractibility can be solved in...

In 1982 Richard P. Stanley conjectured that any finitely generated Zn-graded module M over a finitely generated Nn-graded K-algebra R can be decomposed as a direct sum M = ⊕t i=1 νi Si of finitely many free modules νi Si which have to satisfy some additional conditions. Besides homogeneity conditions the most important restriction is that the Si have to be subalgebras of R of dimension at least...

1. Introduction. When studying ideal theory in semirings, it is natural to consider the quotient structure of a semiring modulo an ideal. If 7 is an ideal in a semiring R, the collection {x+l}xeit oí sets x + I={x+i\iEl} need not be a partition of R. Faced with this problem, [2] used equivalence relations to determine cosets relative to an ideal. La Torre successfully established analogues of s...

IT-enabled exchange in electronic markets has significant implications for buyer-supplier relationships. This paper builds on transaction cost and routine based perspectives in analyzing buyers’ decisions to use reverse auctions, which are an emerging IT-enabled exchange mechanism. The study argues that buyers are less likely to adopt reverse auctions for supplier relationships with high degree...

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In this paper, we analyze the security of cryptosystems using short generators over ideal lattices such as candidate multilinear maps by Garg, Gentry and Halevi and fully homomorphic encryption by Smart and Vercauteren. Our approach is based on a recent work by Cramer, Ducas, Peikert and Regev on analysis of recovering a short generator of an ideal in the q-th cyclotomic field for a prime power...

This paper studies the representations of a non-negative polynomial f on a non-compact semi-algebraic set K modulo its critical ideal. Under the assumption that the semi-algebraic set K is regular and f satisfies the boundary Hessian conditions (BHC) at each zero of f in K. We show that f can be represented as a sum of squares (SOS) of real polynomials modulo its critical ideal if f ≥ 0 on K. P...