Relevance Logic

Relevance logic is a branch of non-classical logic that requires a meaningful connection between premises and conclusions. It avoids the paradoxes of material implication, such as 'if 2+2=5, then the moon is made of cheese'.

The system R, developed by Alan Ross Anderson and Nuel Belnap in 1975, is a prominent relevance logic. Proofs in R can be longer; a theorem that takes 2 steps in classical logic might take 5 steps in R.