set SEQ = Inf_seq S;
deffunc H₁( set , Function of (Inf_seq S),BOOLEAN) -> object = 'not' (Castboolean ($2 . $1));
consider IT being set such that
A1: ( IT in ModelSP (Inf_seq S) & ( for t being set st t in Inf_seq S holds
( H₁(t, Fid (f,(Inf_seq S))) = TRUE iff (Fid (IT,(Inf_seq S))) . t = TRUE ) ) ) from MODELC_1:sch 2();
take IT ; :: thesis: ( IT is Element of ModelSP (Inf_seq S) & ( for t being set st t in Inf_seq S holds
( 'not' (Castboolean ((Fid (f,(Inf_seq S))) . t)) = TRUE iff (Fid (IT,(Inf_seq S))) . t = TRUE ) ) )
thus ( IT is Element of ModelSP (Inf_seq S) & ( for t being set st t in Inf_seq S holds
( 'not' (Castboolean ((Fid (f,(Inf_seq S))) . t)) = TRUE iff (Fid (IT,(Inf_seq S))) . t = TRUE ) ) ) by A1; :: thesis: verum