Simultaneous representations by metric spaces
Some constructions related to Rees matrix rings.
Some decision problems on integer matrices
Given a finite set of matrices with integer entries, consider the question of determining whether the semigroup they generated 1) is free; 2) contains the identity matrix; 3) contains the null matrix or 4) is a group. Even for matrices of dimension , questions 1) and 3) are undecidable. For dimension , they are still open as far as we know. Here we prove that problems 2) and 4) are decidable by proving more generally that it is recursively decidable whether or not a given non singular matrix belongs...
Some decision problems on integer matrices
Given a finite set of matrices with integer entries, consider the question of determining whether the semigroup they generated 1) is free; 2) contains the identity matrix; 3) contains the null matrix or 4) is a group. Even for matrices of dimension 3, questions 1) and 3) are undecidable. For dimension 2, they are still open as far as we know. Here we prove that problems 2) and 4) are decidable by proving more generally that it is recursively decidable whether or not a given non singular matrix belongs...
Some monothetic subsemigroups of S(R).
Some observations on left absolutely flat monoids.
Some open problems and directions for further research in semigroups of continuous selfmaps
Some remarks on finite full transformation semigroups.
Some remarks on T-semigroups
Some results on generalized inverse semigroups.
S-sets and semigroups of quotients.
Subtraction semigroups
A subtraction semigroup is a semigroup with a further operation "" added, called subtraction and satisfying certain axioms. The paper concerns a problem by B. M. Schein concerning the structure of multiplication in a subtraction semigroup.
Sur les automorphismes du demi groupe des applications d'un ensemble dans lui-même
Sur mon article 'une topologie du monoide libre".
Sur une forme de familles de fonctions commutatives
Symmetry classes of tensors via semigroup operands.
Symons’ -congruence on sandwich semigroups