Past exam of the mathematics course of the University of Cambridge / 2002 / iii / Paper 76 / 5 / iii

For the Church numeral system already used, the discriminatorhas $D{c}_{0}UV{\to }_{\beta }^{\ast }U$ and $D{c}_{1}UV{\to }_{\beta }^{\ast }V$ by the Church numeral zero test. More generally it chooses $V$ at every positive numeral. Only its values at zero and one are needed.