It seems, to me that the program/function always terminates.
(Though it doesn't produce the intended result (the function is named 'mu' which I guess, is for multiplication) for a < 0).
And the 'Q' required is just the Loop Invariant (right?), which I think is "y=i*b".
Or am I missing something large, considering that this is for a post grad paper and I've just begun my college education(two weeks, to be exact).
(The whole question paper is here)