consider k being Element of NAT , P being QC-pred_symbol of k,A, ll being QC-variable_list of k,A such that
A1: F = P ! ll by B1, Def18;
reconsider ll = ll as FinSequence of QC-variables A ;
take ll ; :: thesis: ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being QC-variable_list of k,A st
( ll = ll & F = P ! ll )
thus ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being QC-variable_list of k,A st
( ll = ll & F = P ! ll ) by A1; :: thesis: verum