let f be Function of (2 -tuples_on BOOLEAN),BOOLEAN; for x, y, c being non pair object holds InputVertices (2GatesCircStr (x,y,c,f)) is without_pairs
let x, y, c be non pair object ; InputVertices (2GatesCircStr (x,y,c,f)) is without_pairs
InputVertices (2GatesCircStr (x,y,c,f)) = {x,y,c}
by Th57;
hence
InputVertices (2GatesCircStr (x,y,c,f)) is without_pairs
; verum