```* Step 1: WeightGap WORST_CASE(?,O(n^2))
+ Considered Problem:
- Strict TRS:
+(x,0()) -> x
+(x,s(y)) -> s(+(x,y))
sum(0()) -> 0()
sum(s(x)) -> +(sum(x),s(x))
- Signature:
{+/2,sum/1} / {0/0,s/1}
- Obligation:
innermost runtime complexity wrt. defined symbols {+,sum} and constructors {0,s}
+ Applied Processor:
WeightGap {wgDimension = 1, wgDegree = 1, wgKind = Algebraic, wgUArgs = UArgs, wgOn = WgOnAny}
+ Details:
The weightgap principle applies using the following nonconstant growth matrix-interpretation:
We apply a matrix interpretation of kind constructor based matrix interpretation:
The following argument positions are considered usable:
uargs(+) = {1},
uargs(s) = {1}

Following symbols are considered usable:
all
TcT has computed the following interpretation:
p(+) =  x1 + 
p(0) = 
p(s) =  x1 + 
p(sum) =  x1 + 

Following rules are strictly oriented:
+(x,0()) =  x + 
>  x + 
= x

sum(s(x)) =  x + 
>  x + 
= +(sum(x),s(x))

Following rules are (at-least) weakly oriented:
+(x,s(y)) =   x + 
>=  x + 
=  s(+(x,y))

sum(0()) =  
>= 
=  0()

Further, it can be verified that all rules not oriented are covered by the weightgap condition.
* Step 2: MI WORST_CASE(?,O(n^2))
+ Considered Problem:
- Strict TRS:
+(x,s(y)) -> s(+(x,y))
sum(0()) -> 0()
- Weak TRS:
+(x,0()) -> x
sum(s(x)) -> +(sum(x),s(x))
- Signature:
{+/2,sum/1} / {0/0,s/1}
- Obligation:
innermost runtime complexity wrt. defined symbols {+,sum} and constructors {0,s}
+ Applied Processor:
MI {miKind = MaximalMatrix (UpperTriangular (Multiplicity Nothing)), miDimension = 1, miUArgs = UArgs, miURules = URules, miSelector = Just any strict-rules}
+ Details:
We apply a matrix interpretation of kind MaximalMatrix (UpperTriangular (Multiplicity Nothing)):

The following argument positions are considered usable:
uargs(+) = {1},
uargs(s) = {1}

Following symbols are considered usable:
{+,sum}
TcT has computed the following interpretation:
p(+) =  x_1 + 
p(0) = 
p(s) =  x_1 + 
p(sum) = 

Following rules are strictly oriented:
sum(0()) = 
> 
= 0()

Following rules are (at-least) weakly oriented:
+(x,0()) =   x + 
>=  x + 
=  x

+(x,s(y)) =   x + 
>=  x + 
=  s(+(x,y))

sum(s(x)) =  
>= 
=  +(sum(x),s(x))

* Step 3: NaturalPI WORST_CASE(?,O(n^2))
+ Considered Problem:
- Strict TRS:
+(x,s(y)) -> s(+(x,y))
- Weak TRS:
+(x,0()) -> x
sum(0()) -> 0()
sum(s(x)) -> +(sum(x),s(x))
- Signature:
{+/2,sum/1} / {0/0,s/1}
- Obligation:
innermost runtime complexity wrt. defined symbols {+,sum} and constructors {0,s}
+ Applied Processor:
NaturalPI {shape = Mixed 2, restrict = Restrict, uargs = UArgs, urules = URules, selector = Just any strict-rules}
+ Details:
We apply a polynomial interpretation of kind constructor-based(mixed(2)):
The following argument positions are considered usable:
uargs(+) = {1},
uargs(s) = {1}

Following symbols are considered usable:
{+,sum}
TcT has computed the following interpretation:
p(+) = x1 + 2*x2
p(0) = 0
p(s) = 1 + x1
p(sum) = 2*x1 + 2*x1^2

Following rules are strictly oriented:
+(x,s(y)) = 2 + x + 2*y
> 1 + x + 2*y
= s(+(x,y))

Following rules are (at-least) weakly oriented:
+(x,0()) =  x
>= x
=  x

sum(0()) =  0
>= 0
=  0()

sum(s(x)) =  4 + 6*x + 2*x^2
>= 2 + 4*x + 2*x^2
=  +(sum(x),s(x))

* Step 4: EmptyProcessor WORST_CASE(?,O(1))
+ Considered Problem:
- Weak TRS:
+(x,0()) -> x
+(x,s(y)) -> s(+(x,y))
sum(0()) -> 0()
sum(s(x)) -> +(sum(x),s(x))
- Signature:
{+/2,sum/1} / {0/0,s/1}
- Obligation:
innermost runtime complexity wrt. defined symbols {+,sum} and constructors {0,s}
+ Applied Processor:
EmptyProcessor
+ Details:
The problem is already closed. The intended complexity is O(1).

WORST_CASE(?,O(n^2))
```