Proof Outline
l Graph has O(n2) (capacitated) edges
l So O(n2) work to contract, then two
subproblems of size n/2½
» T(n) =  2 T(n/2½) + O(n2) = O(n2 log n)
l Algorithm fails if both iterations fail
» Iteration succeeds if contractions and
recursion succeed
» P(n)=1 - [1 - ½ P(n/2½)]2 = W (1 / log n)