If P∗ is a finer partition than P, then show that L(f,P,α)≤L(f,P∗,α).
explain me how area of rectangle of lower sum is L(p,f,α) = inf f(x). [α(b)-α(a)] and not [inf f(x)- inf α(x)][b-a]
and apart from that how does it even form a rectangle between two functions of f(x) and α(x).