%0 Journal Article
%A V. G. Durnev
%T Undecidability of a~simple fragment of a~positive theory with a~single constant for a~free semigroup of rank two
%J Matematičeskie zametki
%D 2000
%P 191-200
%V 67
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZM_2000_67_2_a2/
%G ru
%F MZM_2000_67_2_a2