McCarthy 91 function, Java version

McCarthy 91 function
Topics: Tricky termination / Historical examples
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/*  The Why platform for program certification                            */
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/*  Copyright (C) 2002-2011                                               */
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/*    Jean-Christophe FILLIATRE, CNRS & Univ. Paris-sud 11                */
/*    Claude MARCHE, INRIA & Univ. Paris-sud 11                           */
/*    Yannick MOY, Univ. Paris-sud 11                                     */
/*    Romain BARDOU, Univ. Paris-sud 11                                   */
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/*    Sylvie BOLDO, INRIA                 (floating-point support)        */
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/* McCarthy's ``91'' function. */

public class MacCarthy {

    /*@ decreases 101-n ;
      @ behavior less_than_101:
      @   assumes n <= 100;
      @   ensures \result == 91;
      @ behavior greater_than_100:
      @   assumes n >= 101;
      @   ensures \result == n - 10;
      @*/
    public static int f91(int n) {
	if (n <= 100) {
	    return f91(f91(n + 11));
	}
	else
	    return n - 10;
    }

}

/*
Local Variables:
compile-command: "make MacCarthy.why3ml"
End:
*/
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McCarthy 91 function, Java version
