let F be Field; for S being SymSp of F
for b, a being Element of S st not a _|_ holds
ProJ (a,b,b) = 1_ F
let S be SymSp of F; for b, a being Element of S st not a _|_ holds
ProJ (a,b,b) = 1_ F
let b, a be Element of S; ( not a _|_ implies ProJ (a,b,b) = 1_ F )
A1:
b - b = 0. S
by RLVECT_1:5;
assume
not a _|_
; ProJ (a,b,b) = 1_ F
hence
ProJ (a,b,b) = 1_ F
by A1, Th11, Th34; verum