Some definitions of interest.
w-E	Def E == {p:(Id)| isnull(a(1of(p);2of(p))) }
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'}
Id	Def Id == Atom
	Thm* Id  Type
w-eq-E	Def p = q == 1of(p) = 1of(q)(2of(p)=2of(q))
assert	Def b == if b True else False fi
	Thm* b:. b  Prop
nat	Def  == {i:| 0i }
	Thm*   Type
not	Def A == A  False
	Thm* A:Prop. (A)  Prop
w-a	Def a(i;t) == 1of(2of(2of(2of(2of(w)))))(i,t)
pi1	Def 1of(t) == t.1
	Thm* A:Type, B:(AType), p:(a:AB(a)). 1of(p)  A
pi2	Def 2of(t) == t.2
	Thm* A:Type, B:(AType), p:(a:AB(a)). 2of(p)  B(1of(p))
w-isnull	Def isnull(a) == isl(a)

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