let T be InsType of SCM ; :: thesis: ( T = 6 implies dom (product" (JumpParts T)) = {1} )
consider i1 being Element of NAT ;
assume A1: T = 6 ; :: thesis: dom (product" (JumpParts T)) = {1}
A2: JumpPart (SCM-goto i1) = <*i1*> by RECDEF_2:def 2;

hereby :: according to TARSKI:def 3,XBOOLE_0:def 10 :: thesis: {1} c= dom (product" (JumpParts T))

let x be set ; :: thesis: ( x in dom (product" (JumpParts T)) implies x in {1} )
InsCode (SCM-goto i1) = 6 by RECDEF_2:def 1;
then A3: JumpPart (SCM-goto i1) in JumpParts T by A1;
assume x in dom (product" (JumpParts T)) ; :: thesis: x in {1}
then x in dom (JumpPart (SCM-goto i1)) by A3, CARD_3:def 13;
hence x in {1} by A2, FINSEQ_1:4, FINSEQ_1:def 8; :: thesis: verum

end;

let x be set ; :: according to TARSKI:def 3 :: thesis: ( not x in {1} or x in dom (product" (JumpParts T)) )
assume A4: x in {1} ; :: thesis: x in dom (product" (JumpParts T))
for f being Function st f in JumpParts T holds
x in dom f

proof

let f be Function; :: thesis: ( f in JumpParts T implies x in dom f )
assume f in JumpParts T ; :: thesis: x in dom f
then consider I being Instruction of SCM such that
A5: f = JumpPart I and
A6: InsCode I = T ;
consider i1 being Element of NAT such that
A7: I = SCM-goto i1 by A1, A6, AMI_5:52;
f = <*i1*> by A5, A7, RECDEF_2:def 2;
hence x in dom f by A4, FINSEQ_1:4, FINSEQ_1:def 8; :: thesis: verum

end;

hence x in dom (product" (JumpParts T)) by CARD_3:def 13; :: thesis: verum