Termination w.r.t. Q of the given QTRS could not be shown:

(0) Obligation:

Q restricted rewrite system:
The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

Q is empty.

(1) AAECC Innermost (EQUIVALENT transformation)

We have applied [NOC,AAECCNOC] to switch to innermost. The TRS R 1 is

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))

The TRS R 2 is

less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The signature Sigma is {less_leaves, false, true}

(2) Obligation:

Q restricted rewrite system:
The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The set Q consists of the following terms:

concat(leaf, x0)
concat(cons(x0, x1), x2)
less_leaves(x0, leaf)
less_leaves(leaf, cons(x0, x1))
less_leaves(cons(x0, x1), cons(x2, x3))

(3) DependencyPairsProof (EQUIVALENT transformation)

Using Dependency Pairs [AG00,LPAR04] we result in the following initial DP problem.

(4) Obligation:

Q DP problem:
The TRS P consists of the following rules:

CONCAT(cons(u, v), y) → CONCAT(v, y)
LESS_LEAVES(cons(u, v), cons(w, z)) → LESS_LEAVES(concat(u, v), concat(w, z))
LESS_LEAVES(cons(u, v), cons(w, z)) → CONCAT(u, v)
LESS_LEAVES(cons(u, v), cons(w, z)) → CONCAT(w, z)

The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The set Q consists of the following terms:

concat(leaf, x0)
concat(cons(x0, x1), x2)
less_leaves(x0, leaf)
less_leaves(leaf, cons(x0, x1))
less_leaves(cons(x0, x1), cons(x2, x3))

We have to consider all minimal (P,Q,R)-chains.

(5) DependencyGraphProof (EQUIVALENT transformation)

The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 2 SCCs with 2 less nodes.

(6) Complex Obligation (AND)

(7) Obligation:

Q DP problem:
The TRS P consists of the following rules:

CONCAT(cons(u, v), y) → CONCAT(v, y)

The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The set Q consists of the following terms:

concat(leaf, x0)
concat(cons(x0, x1), x2)
less_leaves(x0, leaf)
less_leaves(leaf, cons(x0, x1))
less_leaves(cons(x0, x1), cons(x2, x3))

We have to consider all minimal (P,Q,R)-chains.

(8) QDPOrderProof (EQUIVALENT transformation)

We use the reduction pair processor [LPAR04].

The following pairs can be oriented strictly and are deleted.

CONCAT(cons(u, v), y) → CONCAT(v, y)

The remaining pairs can at least be oriented weakly.
Used ordering: Combined order from the following AFS and order.
CONCAT(x1, x2)  =  CONCAT(x1, x2)
cons(x1, x2)  =  cons(x1, x2)
concat(x1, x2)  =  concat(x1, x2)
leaf  =  leaf
less_leaves(x1, x2)  =  less_leaves
false  =  false
true  =  true

Lexicographic path order with status [LPO].
Precedence:

less_leaves > concat₂ > cons₂
less_leaves > false
less_leaves > true

Status:

CONCAT₂: [1,2]
cons₂: [2,1]
concat₂: [1,2]
leaf: []
less_leaves: []
false: []
true: []

The following usable rules [FROCOS05] were oriented:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

(9) Obligation:

Q DP problem:
P is empty.
The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The set Q consists of the following terms:

concat(leaf, x0)
concat(cons(x0, x1), x2)
less_leaves(x0, leaf)
less_leaves(leaf, cons(x0, x1))
less_leaves(cons(x0, x1), cons(x2, x3))

We have to consider all minimal (P,Q,R)-chains.

(10) PisEmptyProof (EQUIVALENT transformation)

The TRS P is empty. Hence, there is no (P,Q,R) chain.

(11) TRUE

(12) Obligation:

Q DP problem:
The TRS P consists of the following rules:

LESS_LEAVES(cons(u, v), cons(w, z)) → LESS_LEAVES(concat(u, v), concat(w, z))

The TRS R consists of the following rules:

concat(leaf, y) → y
concat(cons(u, v), y) → cons(u, concat(v, y))
less_leaves(x, leaf) → false
less_leaves(leaf, cons(w, z)) → true
less_leaves(cons(u, v), cons(w, z)) → less_leaves(concat(u, v), concat(w, z))

The set Q consists of the following terms:

concat(leaf, x0)
concat(cons(x0, x1), x2)
less_leaves(x0, leaf)
less_leaves(leaf, cons(x0, x1))
less_leaves(cons(x0, x1), cons(x2, x3))

We have to consider all minimal (P,Q,R)-chains.