let a, a9, u, u9, v, v9 be Scalar of TernaryFieldEx; ( Tern (u,a,v) = Tern (u9,a,v9) & Tern (u,a9,v) = Tern (u9,a9,v9) & not a = a9 implies u = u9 )
assume A1:
( Tern (u,a,v) = Tern (u9,a,v9) & Tern (u,a9,v) = Tern (u9,a9,v9) )
; ( a = a9 or u = u9 )
reconsider aa = a, aa9 = a9, uu = u, uu9 = u9, vv = v, vv9 = v9 as Real ;
A2:
( Tern (u,a9,v) = (uu * aa9) + vv & Tern (u9,a9,v9) = (uu9 * aa9) + vv9 )
by Def2;
( Tern (u,a,v) = (uu * aa) + vv & Tern (u9,a,v9) = (uu9 * aa) + vv9 )
by Def2;
then
uu * (aa - aa9) = uu9 * (aa - aa9)
by A1, A2;
then
( uu = uu9 or aa - aa9 = 0 )
by XCMPLX_1:5;
hence
( a = a9 or u = u9 )
; verum