Reflexive Graphs with Near Unanimity but no Semilattice Polymorphisms

Electronic Journal Of Combinatorics

Mark Siggers¹ 

关键词: Reflexive Graph;    Polymorphism;    Near Unanimity;    Semilattice;   

DOI  :  

学科分类：离散数学和组合数学

来源: Electronic Journal Of Combinatorics

【 摘 要 】

We show that every generator, in a certain set of generators for the variety of reflexive near unanimity graphs, admits a semilattice polymorphism. We then find a retract of a product of such graphs (paths, in fact) that has no semilattice polymorphism. T

【 授权许可】

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