Satoshi Hada A Note on Transformations of Interactive Proofs that Preserve the Prover's Complexity. 2-9 http://search.ieice.org/bin/summary.php?id=e87-a_1_2&category=D&year=2004&lang=E&abst= 2004 87-A IEICE Transactions 1 db/journals/ieicet/ieicet87a.html#Hada04