let N be with_non-empty_elements set ; for S being non empty IC-Ins-separated Mem-Struct of N
for p being PartState of S
for k being Nat st IC in dom p holds
DecIC ((IncIC (p,k)),k) = p
let S be non empty IC-Ins-separated Mem-Struct of N; for p being PartState of S
for k being Nat st IC in dom p holds
DecIC ((IncIC (p,k)),k) = p
let p be PartState of S; for k being Nat st IC in dom p holds
DecIC ((IncIC (p,k)),k) = p
let k be Nat; ( IC in dom p implies DecIC ((IncIC (p,k)),k) = p )
assume Z:
IC in dom p
; DecIC ((IncIC (p,k)),k) = p
thus DecIC ((IncIC (p,k)),k) =
(IncIC (p,k)) +* (Start-At ((((IC p) + k) -' k),S))
by Th54
.=
(IncIC (p,k)) +* (Start-At ((IC p),S))
by NAT_D:34
.=
p +* (Start-At ((IC p),S))
by Th199
.=
p
by Z, FUNCT_4:7, FUNCT_4:98
; verum