While implemented Amended-Needham-Schroeder, I accidentally wrote the following very subtle bug:Intruder var M : Msg . var N : Nonce . M, N <=> M ; N .rather than the intendedIntruder vars M M1 : Msg . M, M1 <=> M ; M1 .I only realized this was a bug when I was failing to find the expected attack, and I looked at the generated Maude file, in which Isaw the very helpful: -M:Msg, -N:Nonce, +(M:Msg ; N:Nonce) Catching this kind of bug is tricky, because