Combinatorial results for semigroups of order-decreasing partial transformations.
Combinatorial squashings, 3-manifolds, and the third homology of groups.
Combinatorial Structures in Loops.
Combinatoric of syzygies for semigroup algebras.
We describe how the graded minimal resolution of certain semigroup algebras is related to the combinatorics of some simplicial complexes. We obtain characterizations of the Cohen-Macaulay and Gorenstein conditions. The Cohen-Macaulay type is computed from combinatorics. As an application, we compute explicitly the graded minimal resolution of monomial both affine and simplicial projective surfaces.
Combing Euclidean buildings.
Combins of Semidrect Products and 3-Manifold Groups.
Commensurability of graph products.
Commensurations of Out
Let Out(Fn) denote the outer automorphism group of the free group Fn with n>3. We prove that for any finite index subgroup Γ<Out(Fn), the group Aut(Γ) is isomorphic to the normalizer of Γ in Out(Fn). We prove that Γ is co-Hopfian: every injective homomorphism Γ→Γ is surjective. Finally, we prove that the abstract commensurator Comm(Out(Fn)) is isomorphic to Out(Fn).
Commensurations of the Johnson kernel.
Commensurator subgroups of surface groups.
Comments on gentleness of endomorphism algebras.
Comments on the permutation property for semigroups.
Common summands in partitions
Commutation of operations and its relationship with Menger and Mann superpositions
The article considers a problem from Trokhimenko paper [13] concerning the study of abstract properties of commutations of operations and their connection with the Menger and Mann superpositions. Namely, abstract characterizations of some classes of operation algebras, whose signature consists of arbitrary families of commutations of operations, Menger and Mann superpositions and their various connections are found. Some unsolved problems are given at the end of the article.
Commutative and noncommutative invariant theory
Commutative archimedean cancellative semigroups without idempotent
Commutative cancellative semigroups with two generators
Commutative diagrams for the inflation-restriction sequence
Commutative distributive groupoids
Commutative group algebras of highly torsion-complete abelian -groups
A new class of abelian -groups with all high subgroups isomorphic is defined. Commutative modular and semisimple group algebras over such groups are examined. The results obtained continue our recent statements published in Comment. Math. Univ. Carolinae (2002).