groupoidGroupoid2002-02-02 22:46:022002-11-06 19:19:28Definition\usepackage{amssymb}
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%\usepackage{xypic}A groupoid $G$ is a set together with a binary operation $\cdot : G \times G \longrightarrow G$. The groupoid (or ``magma'') is closed under the operation.
There is also a separate, \PMlinkname{category-theoretic}{GroupoidCategoryTheoretic} definition of ``groupoid.''