= Degeneration of a module
{title2=$X\rightsquigarrow Y$}
= Module degeneration
{synonym}
A finite-dimensional <module> $X$ degenerates to $Y$ when $Y$ has a representative in the closure of $X$'s change-of-basis orbit in the <representation variety of an associative algebra>. The full orbit of $Y$ then lies in that closure. The relation is transitive because orbit closures are closed and invariant under change of basis. A <split extension as a degeneration> shows that a module degenerates to the direct sum of its composition factors.
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