-- PHIL1PROOF Derivation of loop[source] Narrowing the preceding formula leads to loop[({a,b,c,d},{f1,f2,f3,f4},{})] Reducts have been simplified. Narrowing the preceding formula leads to loop[({b,c,d},{f3,f4},{a}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,c,d},{f1,f4},{b}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,d},{f1,f2},{c}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,c},{f2,f3},{d}),({a,b,c,d},{f1,f2,f3,f4},{})] Reducts have been simplified. Narrowing the preceding formula leads to loop[({b,d},{},{a,c}),({b,c,d},{f3,f4},{a}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,c,d},{f1,f4},{b}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,d},{f1,f2},{c}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,c},{f2,f3},{d}),({a,b,c,d},{f1,f2,f3,f4},{})] Reducts have been simplified. Narrowing the preceding formula leads to loop[({b,d,a},{f1,f2},{c}),({b,d},{},{a,c}),({b,c,d},{f3,f4},{a}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,c,d},{f1,f4},{b}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,d},{f1,f2},{c}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,c},{f2,f3},{d}),({a,b,c,d},{f1,f2,f3,f4},{})] Reducts have been simplified. Narrowing the preceding formula leads to loop[({b,d,a},{f1,f2},{c}),({b,d},{},{a,c}),({b,c,d},{f3,f4},{a}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,c},{},{b,d}),({a,c,d},{f1,f4},{b}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,d},{f1,f2},{c}),({a,b,c,d},{f1,f2,f3,f4},{})] | loop[({a,b,c},{f2,f3},{d}),({a,b,c,d},{f1,f2,f3,f4},{})] Reducts have been simplified. Narrowing the preceding formula leads to True Reducts have been simplified. Number of proof steps: 6 Solutions: True