Martin Hofmann Donald Sannella On Behavioural Abstraction and Behavioural Satisfaction in Higher-Order Logic. 3-45 1996 167 Theor. Comput. Sci. 1&2 db/journals/tcs/tcs167.html#HofmannS96 http://dx.doi.org/10.1016/0304-3975(96)00068-0