YES
0 QTRS
↳1 QTRSRRRProof (⇔, 31 ms)
↳2 QTRS
↳3 RisEmptyProof (⇔, 0 ms)
↳4 YES
a(a(a(x))) → b(b(x))
b(b(b(x))) → c(d(x))
c(x) → a(a(x))
d(x) → c(x)
With this ordering the following rules can be removed by the rule removal processor [LPAR04] because they are oriented strictly:
POL(a(x1)) = 11 + x1
POL(b(x1)) = 16 + x1
POL(c(x1)) = 23 + x1
POL(d(x1)) = 24 + x1
a(a(a(x))) → b(b(x))
b(b(b(x))) → c(d(x))
c(x) → a(a(x))
d(x) → c(x)