LeeJonesBen-Amram-POPL2001-Ex5_true-termination.c

contents

/*
 * Program from Ex.5 of
 * 2001POPL - Lee,Jones,Ben-Amram - The size-change principle for program termination
 * where we abstracted lists by their size.
 *
 * Date: 12.12.2013
 * Author: heizmann@informatik.uni-freiburg.de
 *
 */

extern int __VERIFIER_nondet_int(void);

int f(int x, int y) {
	if (y == 0) {
		return x;
	} else {
		if (x == 0) {
			return f(y, y-1);
		} else {
			return f(y, x-1);
		}
	}
}

int main() {
	int x = __VERIFIER_nondet_int();
	int y = __VERIFIER_nondet_int();
	if ( x >= 0 && y >= 0) {
		f(x,y);
	}
	return 0;
}

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