Termination of the given JBC could be proven:

(0) Obligation:

JBC Problem based on JBC Program:

/**
 * The classical recursive definition of factorial.
 *
 * All calls terminate.
 *
 * Julia + BinTerm prove that all calls terminate
 *
 * Note that we have to express the basic case as n < 0
 * in order to prove termination.
 *
 * @author <A HREF="mailto:[e-mail]">Fausto Spoto</A>
 */

public class Factorial {
    public static int factorial(int n) {
	if (n < 0) return 1;
	else return n * factorial(n - 1);
    }

    public static void main(String[] args) {
	factorial(10);
    }
}

(1) JBCToGraph (SOUND transformation)

Constructed TerminationGraph.

(2) Obligation:

Termination Graph based on JBC Program:
Factorial.main([Ljava/lang/String;)V: Graph of 131 nodes with 0 SCCs.

(3) TerminationGraphToSCCProof (SOUND transformation)

Proven termination by absence of SCCs

(4) TRUE