There is a unique up to isomorphism axiomatization of Actors here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3418003 https://papers.ssrn.com/sol3/pap

There is a unique up to isomorphism axiomatization of Actors here: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3418003 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3418003 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3459566 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3459566