We consider universal computability of the LCTRS with only rule scheme Calc:

  Signature: eval :: Int -> Int -> o

  Rules: eval(x, y) -> eval(x - 1, x) | x > 0 /\ y > 0
         eval(x, y) -> eval(y - 2, x + 1) | x > 0 /\ y > 0

The system is accessible function passing by a sort ordering that equates all sorts.

We start by computing the initial DP problem D1 = (P1, R UNION R_?, i, c), where:

  P1. (1) eval#(x, y) => eval#(x - 1, x) | x > 0 /\ y > 0
      (2) eval#(x, y) => eval#(y - 2, x + 1) | x > 0 /\ y > 0

***** We apply the Usable Rules Processor on D1 = (P1, R UNION R_?, i, c).

We obtain 0 usable rules (out of 2 rules in the input problem).

Processor output: { D2 = (P1, {}, i, c) }.

***** No progress could be made on DP problem D2 = (P1, {}, i, c).