A reflexive cycle is any reflexive digraph whose underlying undirected graph is a cycle. Call a relational structure Slupecki if its surjective polymorphisms are all essentially unary. We prove that all reflexive cycles of girth at least 4 have this property.
翻译:反射循环是指任何反射分解,其基础的未定向图形是循环。如果其推测性多形态基本上都是非单向的,则称之为关系结构Slupecki。我们证明,至少四层的所有反射周期都具有这一属性。