This was an error in the associative commutative formula simplifier: when all expressions were cancelled, an empty set was returned instead of the type. The code is now much clearer: when the list of arguments becomes empty after simplification, return the neutral element.
This has been fixed in CVS now and will be available in release 0.9.1.
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This was an error in the associative commutative formula simplifier: when all expressions were cancelled, an empty set was returned instead of the type. The code is now much clearer: when the list of arguments becomes empty after simplification, return the neutral element.
This has been fixed in CVS now and will be available in release 0.9.1.