Recursive Function Definitions

Recursive function definitions need not define a function uniquely!

The specification q(x) = (x equals zero) ? one [] q(x plus one)

defines a function in N ? N?. The following functions all satisfy that

specification:

• f 1 (x) = one if x = zero

  ? otherwise
  
  

• f 2 (x) = one if x = zero

  two otherwise
  

• f 3 (x) = one

Previous slide

Next slide

Back to first slide

View graphic version