… essentially different executions. In previous work, we have described a search algorithm to discover the shapes of a protocol, and implemented the algorithm in a Cryptographic Protocol … or regular strands. A’s strand is only partially matching, because the principal A meant to contact is some C which may or may not equal B. There is no alternative: Any diagram containing … symbol, then x · α = x. Strands and Origination. Since replacements map atoms to atoms, not to com- pound terms, unification is very simple. Two terms are unifiable if and only if they have …