POSP

a recognizer for the positive integers
Major Section:  PROGRAMMING

(posp x) is logically equivalent to (not (zp x)) (see zp) and also to (and (natp x) (not (equal x 0))). We recommend the file books/ordinals/natp-posp as a book for reasoning about posp and natp. This book is included in books/arithmetic/top and books/arithmetic/top-with-meta.