lTo
show P([]):
("M) length(append([],
M)) = length([]) + length(M)
lWe
know from the definition of append that
append([],
M) == M.
lWe
also know that
length([]) == 0.
lSo
the thing to be shown reduces to:
("M) length(M) == 0 +
length(M)
which is true since the
equation reduces to an identity.
l