A deceptive fact about functions
The paper provides a proof of a combinatorial result which pertains to the characterization of the set of equations which are solvable in the composition monoid of all partial functions on an infinite set.
Completeness theorem for the Evans logic of identities.
Different levels of word problems for some varieties.
L'ordre de Dehornoy sur les tresses
Morphisms fixing words associated with exchange of three intervals
We consider words coding exchange of three intervals with permutation (3,2,1), here called 3iet words. Recently, a characterization of substitution invariant 3iet words was provided. We study the opposite question: what are the morphisms fixing a 3iet word? We reveal a narrow connection of such morphisms and morphisms fixing Sturmian words using the new notion of amicability.
Morphisms preserving the set of words coding three interval exchange
Any amicable pair ϕ, ψ of Sturmian morphisms enables a construction of a ternary morphism η which preserves the set of infinite words coding 3-interval exchange. We determine the number of amicable pairs with the same incidence matrix in SL±(2,ℕ) and we study incidence matrices associated with the corresponding ternary morphisms η.
Morphisms preserving the set of words coding three interval exchange∗∗∗
Any amicable pair ϕ, ψ of Sturmian morphisms enables a construction of a ternary morphism η which preserves the set of infinite words coding 3-interval exchange. We determine the number of amicable pairs with the same incidence matrix in SL±(2,ℕ) and we study incidence matrices associated with the corresponding ternary morphisms η.
On a variety of infinite algebras
On free Turing algebras
On quasi-algebras and the word problem.
On the structure of equationally complete varieties. I
Positive eigenvalues and two-letter generalized words.
Termal groupoids
We investigate the factor of the groupoid of terms through the largest congruence with a given set among its blocks. The set is supposed to be closed for overterms.
Terms and semiterms
The word problem for regular identities
Undecidable varieties with solvable word problems. II.
Undecidable varieties with solvable word problems. III (a semigroup variety).
Weak subalgebra lattices of monounary partial algebras
Алгоритмические проблемы в многообразиях полугрупп
Критические теории некоторых классов неассоциативных колец