set Ma = Macro (a := b);
let s be 0 -started State of SCM+FSA; :: according to AMISTD_1:def 11,SCMFSA6C:def 1 :: thesis: for b₁ being set holds
( not Macro (a := b) c= b₁ or b₁ halts_on s )
A1: Start-At (0,SCM+FSA) c= s by MEMSTR_0:29;
let P be Instruction-Sequence of SCM+FSA; :: thesis: ( not Macro (a := b) c= P or P halts_on s )
assume A2: Macro (a := b) c= P ; :: thesis: P halts_on s
take 1 ; :: according to EXTPRO_1:def 8 :: thesis: ( IC (Comput (P,s,1)) in proj1 P & CurInstr (P,(Comput (P,s,1))) = halt SCM+FSA )
A4: dom P = NAT by PARTFUN1:def 2;
thus IC (Comput (P,s,1)) in dom P by A4; :: thesis: CurInstr (P,(Comput (P,s,1))) = halt SCM+FSA
dom (Start-At (0,SCM+FSA)) = {(IC )} by FUNCOP_1:13;
then A5: IC in dom (Start-At (0,SCM+FSA)) by TARSKI:def 1;
A6: IC s = (Start-At (0,SCM+FSA)) . (IC ) by A5, A1, GRFUNC_1:2
.= 0 by FUNCOP_1:72 ;
then A7: IC (Exec ((a := b),s)) = succ 0 by SCMFSA_2:63
.= 0 + 1 ;
A8: 1 in dom (Macro (a := b)) by COMPOS_1:60;
A9: 0 in dom (Macro (a := b)) by COMPOS_1:60;
A10: P . 0 = (Macro (a := b)) . 0 by A2, A9, GRFUNC_1:2
.= a := b by COMPOS_1:58 ;
A11: P . 1 = (Macro (a := b)) . 1 by A2, A8, GRFUNC_1:2
.= halt SCM+FSA by COMPOS_1:59 ;
Comput (P,s,(0 + 1)) = Following (P,(Comput (P,s,0))) by EXTPRO_1:3
.= Following (P,s) by EXTPRO_1:2
.= Exec ((a := b),s) by A6, A4, A10, PARTFUN1:def 6 ;
hence CurInstr (P,(Comput (P,s,1))) = halt SCM+FSA by A7, A4, A11, PARTFUN1:def 6; :: thesis: verum