Determine whether the function f: [0,1] R given by:
f(x):=
3 if
1 if \
is Riemann integrable on [0,1].
I know that if it is Riemann integrable, sup L(P, f) = inf U(P,f), P being the partition of [0,1]
or (lower integral of f over [0,1]) = (upper integral of f over [0,1])
How do I show if it is or not?