Sanjay Jain Efim B. Kinber Rolf Wiehagen Thomas Zeugmann On learning of functions refutably. 111-143 2003 1 Theor. Comput. Sci. 298 http://dx.doi.org/10.1016/S0304-3975(02)00421-8 db/journals/tcs/tcs298.html#JainKWZ03