YES

We show the termination of the TRS R:

  app(app(app(consif(),true()),x),ys) -> app(app(cons(),x),ys)
  app(app(app(consif(),false()),x),ys) -> ys
  app(app(filter(),f),nil()) -> nil()
  app(app(filter(),f),app(app(cons(),x),xs)) -> app(app(app(consif(),app(f,x)),x),app(app(filter(),f),xs))

-- SCC decomposition.

Consider the dependency pair problem (P, R), where P consists of

p1: app#(app(app(consif(),true()),x),ys) -> app#(app(cons(),x),ys)
p2: app#(app(app(consif(),true()),x),ys) -> app#(cons(),x)
p3: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(app(app(consif(),app(f,x)),x),app(app(filter(),f),xs))
p4: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(app(consif(),app(f,x)),x)
p5: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(consif(),app(f,x))
p6: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(f,x)
p7: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(app(filter(),f),xs)

and R consists of:

r1: app(app(app(consif(),true()),x),ys) -> app(app(cons(),x),ys)
r2: app(app(app(consif(),false()),x),ys) -> ys
r3: app(app(filter(),f),nil()) -> nil()
r4: app(app(filter(),f),app(app(cons(),x),xs)) -> app(app(app(consif(),app(f,x)),x),app(app(filter(),f),xs))

The estimated dependency graph contains the following SCCs:

  {p6, p7}


-- Reduction pair.

Consider the dependency pair problem (P, R), where P consists of

p1: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(app(filter(),f),xs)
p2: app#(app(filter(),f),app(app(cons(),x),xs)) -> app#(f,x)

and R consists of:

r1: app(app(app(consif(),true()),x),ys) -> app(app(cons(),x),ys)
r2: app(app(app(consif(),false()),x),ys) -> ys
r3: app(app(filter(),f),nil()) -> nil()
r4: app(app(filter(),f),app(app(cons(),x),xs)) -> app(app(app(consif(),app(f,x)),x),app(app(filter(),f),xs))

The set of usable rules consists of

  (no rules)

Take the monotone reduction pair:

  matrix interpretations:
  
    carrier: N^2
    order: standard order
    interpretations:
      app#_A(x1,x2) = ((1,1),(1,1)) x1 + ((1,1),(1,1)) x2
      app_A(x1,x2) = x1 + ((1,1),(1,1)) x2 + (0,1)
      filter_A() = (1,1)
      cons_A() = (1,1)

The next rules are strictly ordered:

  p1, p2
  r1, r2, r3, r4

We remove them from the problem.  Then no dependency pair remains.