(ignored inputs)COMMENT [111] p. 29 ( GCR & ~CR & ~GSCR )
Rewrite Rules:
   [ a -> b,
     b -> f(a,a),
     f(?x,a) -> b ]
Apply Direct Methods...
Inner CPs:
   [ f(?x,b) = b ]
Outer CPs:
   [  ]
not Overlay, check Termination...
unknown/not Terminating
unknown Knuth & Bendix
Linear
unknown Development Closed
unknown Strongly Closed
unknown Weakly-Non-Overlapping & Non-Collapsing & Shallow
inner CP cond (upside-parallel)
innter CP Cond (outside)
unknown Upside-Parallel-Closed/Outside-Closed
(inner) Parallel CPs: (not computed)
unknown Toyama (Parallel CPs)
Simultaneous CPs:
   [ b = f(?x,b),
     f(?x,b) = b ]
unknown Okui (Simultaneous CPs)
unknown Strongly Depth-Preserving & Root-E-Closed/Non-E-Overlapping
unknown Strongly Weight-Preserving & Root-E-Closed/Non-E-Overlapping
check Locally Decreasing Diagrams by Rule Labelling...
Critical Pair <f(?x,b), b> by Rules <0, 2> preceded by [(f,2)]
unknown Diagram Decreasing
check Non-Confluence...
obtain 11 rules by 3 steps unfolding
obtain 100 candidates for checking non-joinability
check by TCAP-Approximation (failure)
check by Ordering(rpo), check by Tree-Automata Approximation (success)
<F,Q,Q_f,Delta> where
   F = {(a,0),(b,0),(f,2),(c_1,0)}
   Q = {q_0,q_1,q_{c_1},q_{a},q_{b}}
   Qf = {q_0,q_1}
   Delta = 
   [ a -> q_{a},
     b -> q_1,
     b -> q_{a},
     b -> q_{b},
     f(q_{c_1},q_{b}) -> q_0,
     f(q_{a},q_{a}) -> q_1,
     f(q_{a},q_{a}) -> q_{a},
     f(q_{a},q_{a}) -> q_{b},
     c_1 -> q_{c_1} ]
Witness for Non-Confluence: <f(c_1,b), b>
Direct Methods: not CR

Combined result: not CR
508.trs: Success(not CR)
NO
(24 msec.)