let i, j, m, n be Element of NAT ; for X being BCK-algebra of i,j,m,n holds X is BCK-algebra of n,j,m,n
let X be BCK-algebra of i,j,m,n; X is BCK-algebra of n,j,m,n
for x, y being Element of X holds Polynom n,j,x,y = Polynom m,n,y,x
proof
let x,
y be
Element of
X;
Polynom n,j,x,y = Polynom m,n,y,x
Polynom i,
j,
x,
y = Polynom m,
n,
y,
x
by Def3;
hence
Polynom n,
j,
x,
y = Polynom m,
n,
y,
x
by Th19;
verum
end;
hence
X is BCK-algebra of n,j,m,n
by Def3; verum