Some definitions of interest.
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'}
IdLnk	Def IdLnk == IdId
	Thm* IdLnk  Type
w-match	Def match(l;t;t') Def == (||snds(l;t)||||rcvs(l;t')||) Def == (||rcvs(l;t')||<||snds(l;t)||+||onlnk(l;m(source(l);t))||)
length	Def ||as|| == Case of as; nil  0 ; a.as'  ||as'||+1  (recursive)
	Thm* A:Type, l:A List. ||l||
	Thm* ||nil||
lsrc	Def source(l) == 1of(l)
	Thm* l:IdLnk. source(l)  Id
w-onlnk	Def onlnk(l;mss) == filter(ms.mlnk(ms) = l;mss)
nat	Def  == {i:| 0i }
	Thm*   Type
w-m	Def m(i;t) == 1of(2of(2of(2of(2of(2of(w))))))(i,t)

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