# Primitive Recursive Function

• Dec 2nd 2010, 03:31 AM
Apprentice123
Primitive Recursive Function
How to show that integer subtraction is primitive recursive function?
• Dec 2nd 2010, 11:24 AM
Soroban
Hello, Apprentice123!

To make it easier (for me), I'll consider positive integers only.

Quote:

Show that integer subtraction is primitive recursive function.

Consider the subtraction: . $a - b$

Let $a_0 = a$

Then: . $a_n \:=\:a_{n-1} - 1\;\text{ for }n = 1,2,3,\hdots\:b.$

. . The answer is: . $a_b$