https://cstheory.stackexchange.com/questions/38803/where-is-...
In particular someone claimed to have found a flaw (which I can not comment on, not a complexity theory person):
'Tardos' function is a monotone function which is 1 on k-cliques and 0 on complete (k-1)-partite graphs. As far as I can tell, Berg and Ulfberg use ONLY these properties in their CNF-DNF approximation proof for CLIQUE, which hence prove that Tardos' function has exponential monotone complexity. Blum's Theorem 6 says that monotone complexity lower bounds by CNF-DNF approximation for monotone functions, give the same NON-monotone lower bound. Hence, Tardos' function have exponential complexity according to Theorem 6 (which is false)'