Confluence properties of weak and strong calculi of explicit substitutions
Abstract
Categorical combinators and more recently ls-calculus have been introduced to provide an explicit treatments of substitutions in the l-calculus. We reintroduce here the ingredients of these calculi in a self-contained and stepwise way, with a special emphasis on confluence properties. The main new results of the paper w.r.t. are the following : - we present a confluent weak calculus of substitutions, where no variable clashes can be feared - we solve a conjecture : ls-calculus is not confluent (it is confluent on ground terms only). This unfortunate result is "repaired" by presenting a confluent version of ls-calculus, named the lEnv-calculus called here the confluent ls-calculus.