Why doesn't Simplify simplify this expression involving Xor:?
In:= Simplify[Xor[a, a, b, c]]
Out= a \[Xor] a \[Xor] b \[Xor] c
The two a's should cancel out, and the answer should be b \[Xor] c.
Strangely, if I omit the last c then Simplify *does* simplify:
In:= Simplify[Xor[a, a, b]]