Boole himself used '+' for 'or', but restricted himself as to when he was allowed to do it (i.e. there was no "true or true = true"; iirc it was Peirce and mayb

Boole himself used '+' for 'or', but restricted himself as to when he was allowed to do it (i.e. there was no "true or true = true"; iirc it was Peirce and maybe others who came up with that).