prop: change (or show) the definition of a proposition identifier

prop P = F;

prop P(FP) = Q;

prop P;

Notes

If a formal parameter starts with an upper case letter, it stands for a proposition. For obvious reasons T and F are not valid formal parameter names!

If a formal parameter name starts with a lower case letter, it stands for a modality. The corresponding actual parameter can be positive or negative and can be an action set identifier, or an explicit list, e.g. Set, -Set, {a,b}, {-a,b}.

If the actual parameter is a modality (positive or negative) containing a single action, you may omit the {}, writing for example

prop Can(a) = <a>T;

but WARNING: it is still a modality parameter, not an action parameter. So if you write

prop P(a) = <a,b>Q,

the action a on the right hand side has NOTHING TO DO with the modality a on the left hand side. You have been warned!

Synonyms

See also