半群伪簇的可约性与可定义性
Reducibility versus definability for pseudovarieties of semigroups
摘要：
很容易证明关于方程$x=y$的隐式签名$σ$可约的伪簇也可以由$σ$ -恒等式定义。我们提出了几个反面的例子，使用签名的伪品种通常被定义。从扩展的Straubing-Thérien层次的正规语言的有序的例子问题也被证明提供了一个积极的例子不等式$x\le y$。
英文摘要：
It is easy to show that a pseudovariety which is reducible with respect to an implicit signature $σ$ for the equation $x=y$ can also be defined by $σ$-identities. We present several negative examples for the converse using signatures in which the pseudovarieties are usually defined. An ordered example issue from the extended Straubing-Thérien hierarchy of regular languages is also shown to provide a positive example for the inequality $x\le y$.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
