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Natural numbers

Natural numbers are usually implemented in the style of Peano Arithmetic. There is a canonical term 0: n a t {\displaystyle 0:{\mathsf {nat}}} for zero. Canonical values larger than zero use iterated applications of a successor function S: n a t → n a t {\displaystyle \mathrm {S} :{\mathsf {nat}}\to {\mathsf {nat}}}.