Hard Life with Weak Binders

We introduce weak binders, a lightweight construct to deal with fresh names in nominal calculi. Weak binders do not define the scope of names as precisely as the standard ν-binders, yet they enjoy strong semantic properties. We provide them with a denotational semantics, an equational theory, and a trace inclusion preorder. Furthermore, we present a trace-preserving mapping between weak binders and ν-binders.