Definitions | t T, x:AB(x), x:A. B(x), x initially@i , vartype(i;x), s = t, Type, Prop, A & B, es is an event system of D, ES, {x:A| B(x) }, x.A(x), {T}, P Q, x. t(x), Dsys, D1 D2, D realizes es. P(es), Id, , MsgA, a = b, if b t else f fi, @i: A, @i: x:T initially x = v, x : t initially x = v |