(0) Obligation:
Q restricted rewrite system:
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
Q is empty.
(1) Overlay + Local Confluence (EQUIVALENT transformation)
The TRS is overlay and locally confluent. By [NOC] we can switch to innermost.
(2) Obligation:
Q restricted rewrite system:
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
(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:
APP(x, y) → HELPA(0, plus(length(x), length(y)), x, y)
APP(x, y) → PLUS(length(x), length(y))
APP(x, y) → LENGTH(x)
APP(x, y) → LENGTH(y)
PLUS(x, s(y)) → PLUS(x, y)
LENGTH(cons(x, y)) → LENGTH(y)
HELPA(c, l, ys, zs) → IF(ge(c, l), c, l, ys, zs)
HELPA(c, l, ys, zs) → GE(c, l)
GE(s(x), s(y)) → GE(x, y)
IF(false, c, l, ys, zs) → HELPB(c, l, greater(ys, zs), smaller(ys, zs))
IF(false, c, l, ys, zs) → GREATER(ys, zs)
IF(false, c, l, ys, zs) → SMALLER(ys, zs)
GREATER(ys, zs) → HELPC(ge(length(ys), length(zs)), ys, zs)
GREATER(ys, zs) → GE(length(ys), length(zs))
GREATER(ys, zs) → LENGTH(ys)
GREATER(ys, zs) → LENGTH(zs)
SMALLER(ys, zs) → HELPC(ge(length(ys), length(zs)), zs, ys)
SMALLER(ys, zs) → GE(length(ys), length(zs))
SMALLER(ys, zs) → LENGTH(ys)
SMALLER(ys, zs) → LENGTH(zs)
HELPB(c, l, cons(y, ys), zs) → HELPA(s(c), l, ys, zs)
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
We have to consider all minimal (P,Q,R)-chains.
(5) DependencyGraphProof (EQUIVALENT transformation)
The approximation of the Dependency Graph [LPAR04,FROCOS05,EDGSTAR] contains 4 SCCs with 15 less nodes.
(6) Complex Obligation (AND)
(7) Obligation:
Q DP problem:
The TRS P consists of the following rules:
GE(s(x), s(y)) → GE(x, y)
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
We have to consider all minimal (P,Q,R)-chains.
(8) Obligation:
Q DP problem:
The TRS P consists of the following rules:
LENGTH(cons(x, y)) → LENGTH(y)
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
We have to consider all minimal (P,Q,R)-chains.
(9) Obligation:
Q DP problem:
The TRS P consists of the following rules:
IF(false, c, l, ys, zs) → HELPB(c, l, greater(ys, zs), smaller(ys, zs))
HELPB(c, l, cons(y, ys), zs) → HELPA(s(c), l, ys, zs)
HELPA(c, l, ys, zs) → IF(ge(c, l), c, l, ys, zs)
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
We have to consider all minimal (P,Q,R)-chains.
(10) Obligation:
Q DP problem:
The TRS P consists of the following rules:
PLUS(x, s(y)) → PLUS(x, y)
The TRS R consists of the following rules:
app(x, y) → helpa(0, plus(length(x), length(y)), x, y)
plus(x, 0) → x
plus(x, s(y)) → s(plus(x, y))
length(nil) → 0
length(cons(x, y)) → s(length(y))
helpa(c, l, ys, zs) → if(ge(c, l), c, l, ys, zs)
ge(x, 0) → true
ge(0, s(x)) → false
ge(s(x), s(y)) → ge(x, y)
if(true, c, l, ys, zs) → nil
if(false, c, l, ys, zs) → helpb(c, l, greater(ys, zs), smaller(ys, zs))
greater(ys, zs) → helpc(ge(length(ys), length(zs)), ys, zs)
smaller(ys, zs) → helpc(ge(length(ys), length(zs)), zs, ys)
helpc(true, ys, zs) → ys
helpc(false, ys, zs) → zs
helpb(c, l, cons(y, ys), zs) → cons(y, helpa(s(c), l, ys, zs))
The set Q consists of the following terms:
app(x0, x1)
plus(x0, 0)
plus(x0, s(x1))
length(nil)
length(cons(x0, x1))
helpa(x0, x1, x2, x3)
ge(x0, 0)
ge(0, s(x0))
ge(s(x0), s(x1))
if(true, x0, x1, x2, x3)
if(false, x0, x1, x2, x3)
greater(x0, x1)
smaller(x0, x1)
helpc(true, x0, x1)
helpc(false, x0, x1)
helpb(x0, x1, cons(x2, x3), x4)
We have to consider all minimal (P,Q,R)-chains.