Je dokázáno, že když A a B jsou ortogonálně σ-úplné komutativní pseudo-BCK-algebry takové, že A je izomorfní s direktním faktorem v B a B je izomorfní s direktním faktorem v A, potom algebry A a B jsou izomorfní. (cs)
It is proved that if A and B are orthogonally σ-complete commutative pseudo-BCK-algebras such that A is isomorphic to a direct factor in B, and B is isomorphic to a direct factor in A, then A and B are isomorphic.
It is proved that if A and B are orthogonally σ-complete commutative pseudo-BCK-algebras such that A is isomorphic to a direct factor in B, and B is isomorphic to a direct factor in A, then A and B are isomorphic. (en)