let A be free preIfWhileAlgebra; :: thesis: for C, I being Element of A
for n being Nat st while (C,I) in (ElementaryInstructions A) |^ n holds
ex i being Nat st
( n = i + 1 & C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i )

set B = ElementaryInstructions A;
A1: ElementaryInstructions A is GeneratorSet of A by Def25;
let C, I be Element of A; :: thesis: for n being Nat st while (C,I) in (ElementaryInstructions A) |^ n holds
ex i being Nat st
( n = i + 1 & C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i )

while (C,I) nin ElementaryInstructions A by Th52;
then A2: while (C,I) nin (ElementaryInstructions A) |^ 0 by Th18;
let n be Nat; :: thesis: ( while (C,I) in (ElementaryInstructions A) |^ n implies ex i being Nat st
( n = i + 1 & C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i ) )

assume A3: while (C,I) in (ElementaryInstructions A) |^ n ; :: thesis: ex i being Nat st
( n = i + 1 & C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i )

then consider i being Nat such that
A4: n = i + 1 by A2, NAT_1:6;
take i ; :: thesis: ( n = i + 1 & C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i )
thus n = i + 1 by A4; :: thesis: ( C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i )
A5: dom (Den ((In (4,(dom the charact of A))),A)) = 2 -tuples_on the carrier of A by Th48;
A6: for o being OperSymbol of A
for p being FinSequence st p in dom (Den (o,A)) & (Den (o,A)) . p in ElementaryInstructions A holds
o <> In (4,(dom the charact of A))
proof
let o be OperSymbol of A; :: thesis: for p being FinSequence st p in dom (Den (o,A)) & (Den (o,A)) . p in ElementaryInstructions A holds
o <> In (4,(dom the charact of A))

let p be FinSequence; :: thesis: ( p in dom (Den (o,A)) & (Den (o,A)) . p in ElementaryInstructions A implies o <> In (4,(dom the charact of A)) )
assume that
A7: p in dom (Den (o,A)) and
A8: (Den (o,A)) . p in ElementaryInstructions A and
A9: o = In (4,(dom the charact of A)) ; :: thesis: contradiction
consider a, b being object such that
A10: a in the carrier of A and
A11: b in the carrier of A and
A12: p = <*a,b*> by A5, A7, A9, FINSEQ_2:137;
reconsider a = a, b = b as Element of A by A10, A11;
(Den (o,A)) . p = while (a,b) by A9, A12;
hence contradiction by A8, Th52; :: thesis: verum
end;
<*C,I*> in dom (Den ((In (4,(dom the charact of A))),A)) by A5, FINSEQ_2:137;
then rng <*C,I*> c= (ElementaryInstructions A) |^ i by A1, A3, A4, A6, Th39;
then {C,I} c= (ElementaryInstructions A) |^ i by FINSEQ_2:127;
hence ( C in (ElementaryInstructions A) |^ i & I in (ElementaryInstructions A) |^ i ) by ZFMISC_1:32; :: thesis: verum