{x1,x2,x3,x4,x5,x6,x7,x8} is finite
proof
(
{x1,x2,x3,x4,x5,x6,x7,x8} = {x1} \/ {x2,x3,x4,x5,x6,x7,x8} &
{x1} is
finite &
{x2,x3,x4,x5,x6,x7,x8} is
finite )
by ENUMSET1:62;
hence
{x1,x2,x3,x4,x5,x6,x7,x8} is
finite
by Lm2;
:: thesis: verum
end;
hence
{x1,x2,x3,x4,x5,x6,x7,x8} is finite
; :: thesis: verum