Problem:
 zeros() -> cons(0(),n__zeros())
 U11(tt(),L) -> U12(tt(),activate(L))
 U12(tt(),L) -> s(length(activate(L)))
 length(nil()) -> 0()
 length(cons(N,L)) -> U11(tt(),activate(L))
 zeros() -> n__zeros()
 activate(n__zeros()) -> zeros()
 activate(X) -> X

Proof:
 Matrix Interpretation Processor: dim=1
  
  interpretation:
   [nil] = 1,
   
   [s](x0) = 2x0,
   
   [length](x0) = 2x0,
   
   [U12](x0, x1) = 4x0 + 4x1,
   
   [activate](x0) = x0,
   
   [U11](x0, x1) = x0 + 4x1,
   
   [tt] = 0,
   
   [cons](x0, x1) = 2x0 + 4x1,
   
   [n__zeros] = 0,
   
   [0] = 0,
   
   [zeros] = 0
  orientation:
   zeros() = 0 >= 0 = cons(0(),n__zeros())
   
   U11(tt(),L) = 4L >= 4L = U12(tt(),activate(L))
   
   U12(tt(),L) = 4L >= 4L = s(length(activate(L)))
   
   length(nil()) = 2 >= 0 = 0()
   
   length(cons(N,L)) = 8L + 4N >= 4L = U11(tt(),activate(L))
   
   zeros() = 0 >= 0 = n__zeros()
   
   activate(n__zeros()) = 0 >= 0 = zeros()
   
   activate(X) = X >= X = X
  problem:
   zeros() -> cons(0(),n__zeros())
   U11(tt(),L) -> U12(tt(),activate(L))
   U12(tt(),L) -> s(length(activate(L)))
   length(cons(N,L)) -> U11(tt(),activate(L))
   zeros() -> n__zeros()
   activate(n__zeros()) -> zeros()
   activate(X) -> X
  Unfolding Processor:
   loop length: 7
   terms:
    U11(tt(),n__zeros())
    U12(tt(),activate(n__zeros()))
    s(length(activate(activate(n__zeros()))))
    s(length(activate(n__zeros())))
    s(length(zeros()))
    s(length(cons(0(),n__zeros())))
    s(U11(tt(),activate(n__zeros())))
   context: s([])
   substitution:
    
   Qed