let p, q, r be Element of CQC-WFF ; :: thesis: for X being Subset of CQC-WFF st X |- p => (q => r) & X |- p => q holds
X |- p => r
let X be Subset of CQC-WFF ; :: thesis: ( X |- p => (q => r) & X |- p => q implies X |- p => r )
assume X |- p => (q => r) ; :: thesis: ( not X |- p => q or X |- p => r )
then X |- (p => q) => (p => r) by Th84;
hence ( not X |- p => q or X |- p => r ) by CQC_THE1:92; :: thesis: verum