let i1 be Element of NAT ; :: thesis: for a being Int-Location holds JUMP (a =0_goto i1) = {i1}
let a be Int-Location ; :: thesis: JUMP (a =0_goto i1) = {i1}
set X = { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ;

now

let x be set ; :: thesis: ( ( x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } implies x in {i1} ) & ( x in {i1} implies x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ) )

A1: now

let Y be set ; :: thesis: ( Y in { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } implies i1 in Y )
assume Y in { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ; :: thesis: i1 in Y
then consider il being Element of NAT such that
A2: Y = NIC ((a =0_goto i1),il) ;
NIC ((a =0_goto i1),il) = {i1,(succ il)} by Th76;
hence i1 in Y by A2, TARSKI:def 2; :: thesis: verum

end;

hereby :: thesis: ( x in {i1} implies x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } )

set il1 = 1;
set il2 = 2;
assume A3: x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ; :: thesis: x in {i1}
A4: NIC ((a =0_goto i1),2) = {i1,(succ 2)} by Th76;
NIC ((a =0_goto i1),2) in { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ;
then x in NIC ((a =0_goto i1),2) by A3, SETFAM_1:def 1;
then A5: ( x = i1 or x = succ 2 ) by A4, TARSKI:def 2;
A6: NIC ((a =0_goto i1),1) = {i1,(succ 1)} by Th76;
NIC ((a =0_goto i1),1) in { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ;
then x in NIC ((a =0_goto i1),1) by A3, SETFAM_1:def 1;
then ( x = i1 or x = succ 1 ) by A6, TARSKI:def 2;
hence x in {i1} by A5, TARSKI:def 1; :: thesis: verum

end;

assume x in {i1} ; :: thesis: x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum }
then A7: x = i1 by TARSKI:def 1;
NIC ((a =0_goto i1),i1) in { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } ;
hence x in meet { (NIC ((a =0_goto i1),il)) where il is Element of NAT : verum } by A7, A1, SETFAM_1:def 1; :: thesis: verum

end;

hence JUMP (a =0_goto i1) = {i1} by TARSKI:1; :: thesis: verum