Knowledge and games in modal semirings

Algebraic logic compacts many small steps of general logical derivation into large steps of equational reasoning. We illustrate this by representing epistemic logic and game logic in modal semirings and modal Kleene algebras. For epistemics we treat the classical wise men puzzle and show how to handle knowledge update and revision algebraically. For games, we generalise the well-known connection between game logic and dynamic logic to modal semirings and link it to predicate transformer semantics, in particular to demonic refinement algebra. The study provides evidence that modal semirings will be able to handle a wide variety of (multi-)modal logics in a uniform algebraic fashion well suited to machine assistance