Nominal/Perm.thy
2010-04-20 Christian Urban renamed "_empty" and "_append" to "_zero" and "_plus"
2010-04-20 Christian Urban removed dead code (nominal cannot deal with argument types of constructors that are functions)
2010-04-20 Christian Urban added comment about abstraction in raw permuations
2010-04-20 Christian Urban optimised the code of define_raw_perm
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