Some definitions of interest.
w-E	Def E == {p:(Id)| isnull(a(1of(p);2of(p))) }
w-loc	Def loc(e) == 1of(e)
w-time	Def time(e) == 2of(e)
world	Def World Def == T:IdIdType Def == TA:IdIdType Def == M:IdLnkIdType Def == (i:Id(x:IdT(i,x)))(i:Idaction(w-action-dec(TA;M;i))) Def == (i:Id({m:Msg(M)| source(mlnk(m)) = i } List))Top
	Thm* World  Type{i'}

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