A characterization of convolution and related operations.
A characterization of countable Butler groups
A characterization of dense languages.
A characterization of dual semigroups without nilpotent ideals.
A characterization of Ext(G,ℤ) assuming (V = L)
We complete the characterization of Ext(G,ℤ) for any torsion-free abelian group G assuming Gödel’s axiom of constructibility plus there is no weakly compact cardinal. In particular, we prove in (V = L) that, for a singular cardinal ν of uncountable cofinality which is less than the first weakly compact cardinal and for every sequence of cardinals satisfying (where Π is the set of all primes), there is a torsion-free abelian group G of size ν such that equals the p-rank of Ext(G,ℤ) for every...
A characterization of Fuchsian groups acting on complex hyperbolic spaces
Let be a non-elementary complex hyperbolic Kleinian group. If preserves a complex line, then is -Fuchsian; if preserves a Lagrangian plane, then is -Fuchsian; is Fuchsian if is either -Fuchsian or -Fuchsian. In this paper, we prove that if the traces of all elements in are real, then is Fuchsian. This is an analogous result of Theorem V.G. 18 of B. Maskit, Kleinian Groups, Springer-Verlag, Berlin, 1988, in the setting of complex hyperbolic isometric groups. As an application...
A Characterization of GL(2, 3) and SL(2,5) by the Degrees of their Representations.
A characterization of groups in the class of *-regular semigroups.
A characterization of in terms of the number of character zeros.
A characterization of left cancellative monoids by flatness properties.
A Characterization of Ln (q) as a Permutation Group.
A characterization of minimal zero-sequences of index one in finite cyclic groups.
A characterization of ordered groups by means of segments
A characterization of rational star languages generated by strong codes.
A characterization of regular le-semigroups.
A characterization of regular monoids by flatness of left acts.
A characterization of semigroups which are semilattices of groups
A characterization of semilattices of left groups
A characterization of semilattices of left or right groups
A characterization of sequences with the minimum number of k-sums modulo k
Let G be an additive abelian group of order k, and S be a sequence over G of length k+r, where 1 ≤ r ≤ k-1. We call the sum of k terms of S a k-sum. We show that if 0 is not a k-sum, then the number of k-sums is at least r+2 except for S containing only two distinct elements, in which case the number of k-sums equals r+1. This result improves the Bollobás-Leader theorem, which states that there are at least r+1 k-sums if 0 is not a k-sum.