We determine all quasivarieties of aperiodic semigroups that are contained in some residually finite variety. This endeavor was initially motivated by a problem in natural dualities, but our work here also serves as a partial correction to an error found in a result of Sapir from the 1980s.

中文翻译：

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半群拟变量：两个格和一个重新打开的问题

我们确定了包含在一些剩余有限簇中的非周期半群的所有拟变量。这项努力最初是由自然对偶中的一个问题引起的，但我们在这里的工作也可以作为对 1980 年代 Sapir 结果中发现的错误的部分纠正。