d-partial-world(D;f;t';s;d)
== <i,x. M(i).ds(x)
== , i,a. M(i).da(locl(a))
== , l,tg. M(source(l)).dout(l,tg)
== , i,t. if t <z t' then (f(t,i)).1 else s(i) fi
== , i,t. if t <z t' then ((f(t,i)).2).1 else null fi
== , i,t. if t <z t' then (f(t,i)).2.2 else [] fi
== , i.NullMachine
== , d == , >
d-partial-world(D;f;t';s;d)
== <i,x. d-m(D; i).ds(x)
== , i,a. d-m(D; i).da(locl(a))
== , l,tg. d-m(D; source(l)).dout(l,tg)
== , i,t. if t <z t' then (f(t,i)).1 else s(i) fi
== , i,t. if t <z t' then ((f(t,i)).2).1 else null fi
== , i,t. if t <z t' then (f(t,i)).2.2 else [] fi
== , i.NullMachine
== , d == , >