What problem can occur when a programmer fails to specify the base case or to reduce the size of the problem in a way that terminates the recursive process?

Inifinite loop will occur.

Explanation:

For instance the code block below will result in an infinite loop:

int prev (x) {

Return prev (x-1);

}

The base case is what determine when the function should stop calling itself; if it is absent, infinite loop will occur.

In the above code, a base case of when x = 0 or x = 1 should have been added to avoid the infinite loop.