Termination Proof using AProVE

Term Rewriting System R:
[y, t, l, t', l', s, x, s', x', k, z]
and(true, y) -> y
and(false, y) -> false
eq(nil, nil) -> true
eq(cons(t, l), nil) -> false
eq(nil, cons(t, l)) -> false
eq(cons(t, l), cons(t', l')) -> and(eq(t, t'), eq(l, l'))
eq(var(l), var(l')) -> eq(l, l')
eq(var(l), apply(t, s)) -> false
eq(var(l), lambda(x, t)) -> false
eq(apply(t, s), var(l)) -> false
eq(apply(t, s), apply(t', s')) -> and(eq(t, t'), eq(s, s'))
eq(apply(t, s), lambda(x, t)) -> false
eq(lambda(x, t), var(l)) -> false
eq(lambda(x, t), apply(t, s)) -> false
eq(lambda(x, t), lambda(x', t')) -> and(eq(x, x'), eq(t, t'))
if(true, var(k), var(l')) -> var(k)
if(false, var(k), var(l')) -> var(l')
ren(var(l), var(k), var(l')) -> if(eq(l, l'), var(k), var(l'))
ren(x, y, apply(t, s)) -> apply(ren(x, y, t), ren(x, y, s))
ren(x, y, lambda(z, t)) -> lambda(var(cons(x, cons(y, cons(lambda(z, t), nil)))), ren(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)))

Termination of R to be shown.

     ↳Overlay and local confluence Check

The TRS is overlay and locally confluent (all critical pairs are trivially joinable).Hence, we can switch to innermost.

     ↳OC

       →TRS2

         ↳Dependency Pair Analysis

R contains the following Dependency Pairs:

EQ(cons(t, l), cons(t', l')) -> AND(eq(t, t'), eq(l, l'))
EQ(cons(t, l), cons(t', l')) -> EQ(t, t')
EQ(cons(t, l), cons(t', l')) -> EQ(l, l')
EQ(var(l), var(l')) -> EQ(l, l')
EQ(apply(t, s), apply(t', s')) -> AND(eq(t, t'), eq(s, s'))
EQ(apply(t, s), apply(t', s')) -> EQ(t, t')
EQ(apply(t, s), apply(t', s')) -> EQ(s, s')
EQ(lambda(x, t), lambda(x', t')) -> AND(eq(x, x'), eq(t, t'))
EQ(lambda(x, t), lambda(x', t')) -> EQ(x, x')
EQ(lambda(x, t), lambda(x', t')) -> EQ(t, t')
REN(var(l), var(k), var(l')) -> IF(eq(l, l'), var(k), var(l'))
REN(var(l), var(k), var(l')) -> EQ(l, l')
REN(x, y, apply(t, s)) -> REN(x, y, t)
REN(x, y, apply(t, s)) -> REN(x, y, s)
REN(x, y, lambda(z, t)) -> REN(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t))
REN(x, y, lambda(z, t)) -> REN(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)

Furthermore, R contains two SCCs.

     ↳OC

       →TRS2

         ↳DPs

           →DP Problem 1

             ↳Usable Rules (Innermost)

           →DP Problem 2

             ↳Neg POLO

Dependency Pairs:

EQ(lambda(x, t), lambda(x', t')) -> EQ(t, t')
EQ(lambda(x, t), lambda(x', t')) -> EQ(x, x')
EQ(apply(t, s), apply(t', s')) -> EQ(s, s')
EQ(apply(t, s), apply(t', s')) -> EQ(t, t')
EQ(var(l), var(l')) -> EQ(l, l')
EQ(cons(t, l), cons(t', l')) -> EQ(l, l')
EQ(cons(t, l), cons(t', l')) -> EQ(t, t')

Rules:

and(true, y) -> y
and(false, y) -> false
eq(nil, nil) -> true
eq(cons(t, l), nil) -> false
eq(nil, cons(t, l)) -> false
eq(cons(t, l), cons(t', l')) -> and(eq(t, t'), eq(l, l'))
eq(var(l), var(l')) -> eq(l, l')
eq(var(l), apply(t, s)) -> false
eq(var(l), lambda(x, t)) -> false
eq(apply(t, s), var(l)) -> false
eq(apply(t, s), apply(t', s')) -> and(eq(t, t'), eq(s, s'))
eq(apply(t, s), lambda(x, t)) -> false
eq(lambda(x, t), var(l)) -> false
eq(lambda(x, t), apply(t, s)) -> false
eq(lambda(x, t), lambda(x', t')) -> and(eq(x, x'), eq(t, t'))
if(true, var(k), var(l')) -> var(k)
if(false, var(k), var(l')) -> var(l')
ren(var(l), var(k), var(l')) -> if(eq(l, l'), var(k), var(l'))
ren(x, y, apply(t, s)) -> apply(ren(x, y, t), ren(x, y, s))
ren(x, y, lambda(z, t)) -> lambda(var(cons(x, cons(y, cons(lambda(z, t), nil)))), ren(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)))

Strategy:

innermost

As we are in the innermost case, we can delete all 20 non-usable-rules.

     ↳OC

       →TRS2

         ↳DPs

           →DP Problem 1

             ↳UsableRules

...

               →DP Problem 3

                 ↳Size-Change Principle

           →DP Problem 2

             ↳Neg POLO

Dependency Pairs:

Rule:

none

Strategy:

innermost

We number the DPs as follows:

EQ(lambda(x, t), lambda(x', t')) -> EQ(t, t')
EQ(lambda(x, t), lambda(x', t')) -> EQ(x, x')
EQ(apply(t, s), apply(t', s')) -> EQ(s, s')
EQ(apply(t, s), apply(t', s')) -> EQ(t, t')
EQ(var(l), var(l')) -> EQ(l, l')
EQ(cons(t, l), cons(t', l')) -> EQ(l, l')
EQ(cons(t, l), cons(t', l')) -> EQ(t, t')

and get the following Size-Change Graph(s):

{1, 2, 3, 4, 5, 6, 7}	,	{1, 2, 3, 4, 5, 6, 7}
1	>	1
2	>	2

which lead(s) to this/these maximal multigraph(s):

{1, 2, 3, 4, 5, 6, 7}	,	{1, 2, 3, 4, 5, 6, 7}
1	>	1
2	>	2

D_P: empty set
Oriented Rules: none

We used the order Homeomorphic Embedding Order with Non-Strict Precedence.

trivial

with Argument Filtering System:

apply(x₁, x₂) -> apply(x₁, x₂)
var(x₁) -> var(x₁)
cons(x₁, x₂) -> cons(x₁, x₂)
lambda(x₁, x₂) -> lambda(x₁, x₂)

We obtain no new DP problems.

     ↳OC

       →TRS2

         ↳DPs

           →DP Problem 1

             ↳UsableRules

           →DP Problem 2

             ↳Negative Polynomial Order

Dependency Pairs:

REN(x, y, lambda(z, t)) -> REN(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)
REN(x, y, lambda(z, t)) -> REN(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t))
REN(x, y, apply(t, s)) -> REN(x, y, s)
REN(x, y, apply(t, s)) -> REN(x, y, t)

Rules:

and(true, y) -> y
and(false, y) -> false
eq(nil, nil) -> true
eq(cons(t, l), nil) -> false
eq(nil, cons(t, l)) -> false
eq(cons(t, l), cons(t', l')) -> and(eq(t, t'), eq(l, l'))
eq(var(l), var(l')) -> eq(l, l')
eq(var(l), apply(t, s)) -> false
eq(var(l), lambda(x, t)) -> false
eq(apply(t, s), var(l)) -> false
eq(apply(t, s), apply(t', s')) -> and(eq(t, t'), eq(s, s'))
eq(apply(t, s), lambda(x, t)) -> false
eq(lambda(x, t), var(l)) -> false
eq(lambda(x, t), apply(t, s)) -> false
eq(lambda(x, t), lambda(x', t')) -> and(eq(x, x'), eq(t, t'))
if(true, var(k), var(l')) -> var(k)
if(false, var(k), var(l')) -> var(l')
ren(var(l), var(k), var(l')) -> if(eq(l, l'), var(k), var(l'))
ren(x, y, apply(t, s)) -> apply(ren(x, y, t), ren(x, y, s))
ren(x, y, lambda(z, t)) -> lambda(var(cons(x, cons(y, cons(lambda(z, t), nil)))), ren(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)))

Strategy:

innermost

The following Dependency Pairs can be strictly oriented using the given order.

REN(x, y, lambda(z, t)) -> REN(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)
REN(x, y, lambda(z, t)) -> REN(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t))

Moreover, the following usable rules (regarding the implicit AFS) are oriented.

eq(var(l), apply(t, s)) -> false
eq(var(l), var(l')) -> eq(l, l')
eq(apply(t, s), apply(t', s')) -> and(eq(t, t'), eq(s, s'))
eq(lambda(x, t), apply(t, s)) -> false
eq(cons(t, l), nil) -> false
eq(var(l), lambda(x, t)) -> false
ren(x, y, apply(t, s)) -> apply(ren(x, y, t), ren(x, y, s))
ren(var(l), var(k), var(l')) -> if(eq(l, l'), var(k), var(l'))
ren(x, y, lambda(z, t)) -> lambda(var(cons(x, cons(y, cons(lambda(z, t), nil)))), ren(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)))
eq(apply(t, s), var(l)) -> false
eq(nil, nil) -> true
eq(lambda(x, t), lambda(x', t')) -> and(eq(x, x'), eq(t, t'))
and(true, y) -> y
and(false, y) -> false
eq(cons(t, l), cons(t', l')) -> and(eq(t, t'), eq(l, l'))
if(false, var(k), var(l')) -> var(l')
eq(apply(t, s), lambda(x, t)) -> false
if(true, var(k), var(l')) -> var(k)
eq(nil, cons(t, l)) -> false
eq(lambda(x, t), var(l)) -> false

Used ordering:
Polynomial Order with Interpretation:

POL( REN(x₁, ..., x₃) ) = x₃

POL( lambda(x₁, x₂) ) = x₂ + 1

POL( ren(x₁, ..., x₃) ) = x₃

POL( apply(x₁, x₂) ) = x₁ + x₂

POL( eq(x₁, x₂) ) = 0

POL( false ) = 0

POL( and(x₁, x₂) ) = x₂

POL( var(x₁) ) = 0

POL( if(x₁, ..., x₃) ) = 0

POL( true ) = 0

This results in one new DP problem.

     ↳OC

       →TRS2

         ↳DPs

           →DP Problem 1

             ↳UsableRules

           →DP Problem 2

             ↳Neg POLO

...

               →DP Problem 4

                 ↳Usable Rules (Innermost)

Dependency Pairs:

REN(x, y, apply(t, s)) -> REN(x, y, s)
REN(x, y, apply(t, s)) -> REN(x, y, t)

Rules:

and(true, y) -> y
and(false, y) -> false
eq(nil, nil) -> true
eq(cons(t, l), nil) -> false
eq(nil, cons(t, l)) -> false
eq(cons(t, l), cons(t', l')) -> and(eq(t, t'), eq(l, l'))
eq(var(l), var(l')) -> eq(l, l')
eq(var(l), apply(t, s)) -> false
eq(var(l), lambda(x, t)) -> false
eq(apply(t, s), var(l)) -> false
eq(apply(t, s), apply(t', s')) -> and(eq(t, t'), eq(s, s'))
eq(apply(t, s), lambda(x, t)) -> false
eq(lambda(x, t), var(l)) -> false
eq(lambda(x, t), apply(t, s)) -> false
eq(lambda(x, t), lambda(x', t')) -> and(eq(x, x'), eq(t, t'))
if(true, var(k), var(l')) -> var(k)
if(false, var(k), var(l')) -> var(l')
ren(var(l), var(k), var(l')) -> if(eq(l, l'), var(k), var(l'))
ren(x, y, apply(t, s)) -> apply(ren(x, y, t), ren(x, y, s))
ren(x, y, lambda(z, t)) -> lambda(var(cons(x, cons(y, cons(lambda(z, t), nil)))), ren(x, y, ren(z, var(cons(x, cons(y, cons(lambda(z, t), nil)))), t)))

Strategy:

innermost

As we are in the innermost case, we can delete all 20 non-usable-rules.

     ↳OC

       →TRS2

         ↳DPs

           →DP Problem 1

             ↳UsableRules

           →DP Problem 2

             ↳Neg POLO

...

               →DP Problem 5

                 ↳Size-Change Principle

Dependency Pairs:

REN(x, y, apply(t, s)) -> REN(x, y, s)
REN(x, y, apply(t, s)) -> REN(x, y, t)

Rule:

none

Strategy:

innermost

We number the DPs as follows:

REN(x, y, apply(t, s)) -> REN(x, y, s)
REN(x, y, apply(t, s)) -> REN(x, y, t)

and get the following Size-Change Graph(s):

{1, 2}	,	{1, 2}
1	=	1
2	=	2
3	>	3

which lead(s) to this/these maximal multigraph(s):

{1, 2}	,	{1, 2}
1	=	1
2	=	2
3	>	3

D_P: empty set
Oriented Rules: none

We used the order Homeomorphic Embedding Order with Non-Strict Precedence.

trivial

with Argument Filtering System:

apply(x₁, x₂) -> apply(x₁, x₂)

We obtain no new DP problems.

Termination of R successfully shown.
Duration:
0:03 minutes