The Runtime Complexity (full) of the given CpxTRS could be proven to be BOUNDS(n^1, INF).

(0) Obligation:

Runtime Complexity TRS:
The TRS R consists of the following rules:

le(0, y) → true
le(s(x), 0) → false
le(s(x), s(y)) → le(x, y)
mod(x, 0) → modZeroErro
mod(x, s(y)) → modIter(x, s(y), 0, 0)
modIter(x, s(y), z, u) → if(le(x, z), x, s(y), z, u)
if(true, x, y, z, u) → u
if(false, x, y, z, u) → if2(le(y, s(u)), x, y, s(z), s(u))
if2(false, x, y, z, u) → modIter(x, y, z, u)
if2(true, x, y, z, u) → modIter(x, y, z, 0)

Rewrite Strategy: FULL

(1) CpxTrsToCpxRelTrsProof (BOTH BOUNDS(ID, ID) transformation)

Transformed TRS to relative TRS where S is empty.

(2) Obligation:

Runtime Complexity Relative TRS:
The TRS R consists of the following rules:

le(0, y) → true
le(s(x), 0) → false
le(s(x), s(y)) → le(x, y)
mod(x, 0) → modZeroErro
mod(x, s(y)) → modIter(x, s(y), 0, 0)
modIter(x, s(y), z, u) → if(le(x, z), x, s(y), z, u)
if(true, x, y, z, u) → u
if(false, x, y, z, u) → if2(le(y, s(u)), x, y, s(z), s(u))
if2(false, x, y, z, u) → modIter(x, y, z, u)
if2(true, x, y, z, u) → modIter(x, y, z, 0)

S is empty.
Rewrite Strategy: FULL

(3) DecreasingLoopProof (EQUIVALENT transformation)

The following loop(s) give(s) rise to the lower bound Ω(n¹):
The rewrite sequence
le(s(x), s(y)) →⁺ le(x, y)
gives rise to a decreasing loop by considering the right hand sides subterm at position [].
The pumping substitution is [x / s(x), y / s(y)].
The result substitution is [ ].

(4) BOUNDS(n^1, INF)