consider X being non empty set such that
A1:
proj2 SCM-Instr c= X *
by FINSEQ_1:85;
take
X
; COMPOS_0:def 1 SCM-Instr c= [:NAT,(NAT *),(X *):]
A2:
SCM-Instr c= [:NAT,(NAT *),(proj2 SCM-Instr):]
by Th8;
[:NAT,(NAT *),(proj2 SCM-Instr):] c= [:NAT,(NAT *),(X *):]
by A1, MCART_1:73;
hence
SCM-Instr c= [:NAT,(NAT *),(X *):]
by A2; verum