We prove that Multicut in directed graphs, parameterized by the size of the cutset, is W [1]-hard and hence unlikely to be fixed-parameter tractable even if restricted to instances with only four terminal pairs. This negative result almost completely resolves one of the central open problems in the area of parameterized complexity of graph separation problems, posted originally by Marx and Razg...

We study the Cu5O4 cluster by exact diagonalization of a three-band Hubbard model and show that bound electron or hole pairs are obtained at appropriate fillings, and produce superconducting flux quantisation. The results extend earlier cluster studies and illustrate a canonical transformation approach to pairing that we have developed recently for the full plane. The quasiparticles that in the...

BACKGROUND Participation of compatible pairs (CP) in kidney paired donation (KPD) could be attractive to CPs who have a high degree of HLA mismatch, if the CP recipient will gain a better HLA match. Because KPD programs were not designed to help CP, it is important to define allocation metrics that enable CP to receive a better-matched kidney, without disadvantage to incompatible pairs (ICP). ...

A common ancestor of two vertices u, v in a directed acyclic graph is a vertex w that can reach both. A {u, v}-junction is a common ancestor w so that there are two paths, one from w to u and the other from w to v, that are internally vertex-disjoint. A lowest common ancestor (LCA) of u and v is a common ancestor w so that no other common ancestor of u and v is reachable from w. Every {u, v}-LC...

PAGE INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Nomenclature and descriptions.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Material. ....................................................................... Methods. .........................

Superinfection of an Escherichia coli R(+) strain with a closely related R-factor was associated with the accumulation of replicative intermediates of the superinfecting deoxyribonucleic acid. This deoxyribonucleic acid remains associated with a rapidly sedimenting cell component.

Higman has defined coset diagrams for PGL(2, ℤ). The coset diagrams are composed of fragments, and the fragments are further composed of two or more circuits. A condition for the existence of a certain fragment γ in a coset diagram is a polynomial f in ℤ[𝔃], obtained by choosing a pair of words F[w i , w j ] such that both w i and w j fix a vertex v in γ. Two pairs of words are equivalent if an...

Given a textstring x of n symbols aJld an illtcgcr constant. d, we consider the problem of finding, for any pair (H, =) of subwords of x the number of times that yand z occur in tandem (i.e., with no intermediate occurrence of either one of them) within a distance of d symbols of x. Although in principle there might be Ij4 distind subword pairs in X, we show that it suffices to consider a famil...

An accurate determination of the Higgs decay branching ratios to b ¯ b, c¯ c, gg, W W * and τ + τ − pairs is important for the study of the Higgs couplings and for determining its SM or MSSM nature in the mass range 100 GeV/c 2 < M H < 140 GeV/c 2. This measurement also represents an important benchmark for the optimisation of the detector design. The accuracy on the determination of the Higgs ...