let A be QC-alphabet ; :: thesis: for p being Element of CQC-WFF A st p is atomic holds
ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being CQC-variable_list of k,A st p = P ! ll
let p be Element of CQC-WFF A; :: thesis: ( p is atomic implies ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being CQC-variable_list of k,A st p = P ! ll )
assume p is atomic ; :: thesis: ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being CQC-variable_list of k,A st p = P ! ll
then 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: p = P ! ll by QC_LANG1:def 18;
A2: { (ll . m) where m is Element of NAT : ( 1 <= m & m <= len ll & ll . m in fixed_QC-variables A ) } = {} by A1, CQC_LANG:7;
{ (ll . i) where i is Element of NAT : ( 1 <= i & i <= len ll & ll . i in free_QC-variables A ) } = {} by A1, CQC_LANG:7;
then ll is CQC-variable_list of k,A by A2, CQC_LANG:5;
hence ex k being Element of NAT ex P being QC-pred_symbol of k,A ex ll being CQC-variable_list of k,A st p = P ! ll by A1; :: thesis: verum