1. Subtraction algebras and BCK-algebras Creator: Kim, Young Hee and Kim, Hee Sik Format: bez média and svazek Type: model:article and TEXT Subject: subtraction algebra, subtraction semigroup, implicative BCK-algebra, and BCI-semigroup Language: English Description: In this note we show that a subtraction algebra is equivalent to an implicative BCK-algebra, and a subtraction semigroup is a special case of a BCI-semigroup. Rights: http://creativecommons.org/publicdomain/mark/1.0/ and policy:public