Temporal logic of actions


Temporal logic of actions is a logic developed by Leslie Lamport, which combines temporal logic with a logic of actions.
It is used to describe behaviours of concurrent systems.

Details

Statements in temporal logic are of the form, where A is an action and t contains a subset of the variables appearing in A. An action is an expression containing primed and non-primed variables, such as. The meaning of the non-primed variables is the variable's value in this state. The meaning of primed variables is the variable's value in the next state.
The above expression means the value of x today, plus the value of x tomorrow times the value of y today, equals the value of y tomorrow.
The meaning of is that either A is valid now, or the variables appearing in t do not change. This allows for stuttering steps, in which none of the program variables change their values.