YES
We show the termination of the TRS R:

  app(app(map(),f),nil()) -> nil()
  app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs))
  app(flatten(),app(app(node(),x),xs)) -> app(app(cons(),x),app(concat(),app(app(map(),flatten()),xs)))
  app(concat(),nil()) -> nil()
  app(concat(),app(app(cons(),x),xs)) -> app(app(append(),x),app(concat(),xs))
  app(app(append(),nil()),xs) -> xs
  app(app(append(),app(app(cons(),x),xs)),ys) -> app(app(cons(),x),app(app(append(),xs),ys))

Instead we prove termination of the uncurried system:

  app(append_0(),y) -> append_1(y)
  app(append_1(x1),y) -> append_2(x1,y)
  app(concat_0(),y) -> concat_1(y)
  app(cons_0(),y) -> cons_1(y)
  app(cons_1(x1),y) -> cons_2(x1,y)
  app(flatten_0(),y) -> flatten_1(y)
  app(map_0(),y) -> map_1(y)
  app(map_1(x1),y) -> map_2(x1,y)
  app(node_0(),y) -> node_1(y)
  app(node_1(x1),y) -> node_2(x1,y)
  map_2(f,nil_0()) -> nil_0()
  map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs))
  flatten_1(node_2(x,xs)) -> cons_2(x,concat_1(map_2(flatten_0(),xs)))
  concat_1(nil_0()) -> nil_0()
  concat_1(cons_2(x,xs)) -> append_2(x,concat_1(xs))
  append_2(nil_0(),xs) -> xs
  append_2(cons_2(x,xs),ys) -> cons_2(x,append_2(xs,ys))


-- SCC decomposition.

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

p1: app#(append_1(x1),y) -> append_2#(x1,y)
p2: app#(concat_0(),y) -> concat_1#(y)
p3: app#(flatten_0(),y) -> flatten_1#(y)
p4: app#(map_1(x1),y) -> map_2#(x1,y)
p5: map_2#(f,cons_2(x,xs)) -> app#(f,x)
p6: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs)
p7: flatten_1#(node_2(x,xs)) -> concat_1#(map_2(flatten_0(),xs))
p8: flatten_1#(node_2(x,xs)) -> map_2#(flatten_0(),xs)
p9: concat_1#(cons_2(x,xs)) -> append_2#(x,concat_1(xs))
p10: concat_1#(cons_2(x,xs)) -> concat_1#(xs)
p11: append_2#(cons_2(x,xs),ys) -> append_2#(xs,ys)

and R consists of:

r1: app(append_0(),y) -> append_1(y)
r2: app(append_1(x1),y) -> append_2(x1,y)
r3: app(concat_0(),y) -> concat_1(y)
r4: app(cons_0(),y) -> cons_1(y)
r5: app(cons_1(x1),y) -> cons_2(x1,y)
r6: app(flatten_0(),y) -> flatten_1(y)
r7: app(map_0(),y) -> map_1(y)
r8: app(map_1(x1),y) -> map_2(x1,y)
r9: app(node_0(),y) -> node_1(y)
r10: app(node_1(x1),y) -> node_2(x1,y)
r11: map_2(f,nil_0()) -> nil_0()
r12: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs))
r13: flatten_1(node_2(x,xs)) -> cons_2(x,concat_1(map_2(flatten_0(),xs)))
r14: concat_1(nil_0()) -> nil_0()
r15: concat_1(cons_2(x,xs)) -> append_2(x,concat_1(xs))
r16: append_2(nil_0(),xs) -> xs
r17: append_2(cons_2(x,xs),ys) -> cons_2(x,append_2(xs,ys))

The estimated dependency graph contains the following SCCs:

  {p3, p4, p5, p6, p8}
  {p10}
  {p11}


-- Reduction pair.

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

p1: map_2#(f,cons_2(x,xs)) -> app#(f,x)
p2: app#(map_1(x1),y) -> map_2#(x1,y)
p3: map_2#(f,cons_2(x,xs)) -> map_2#(f,xs)
p4: app#(flatten_0(),y) -> flatten_1#(y)
p5: flatten_1#(node_2(x,xs)) -> map_2#(flatten_0(),xs)

and R consists of:

r1: app(append_0(),y) -> append_1(y)
r2: app(append_1(x1),y) -> append_2(x1,y)
r3: app(concat_0(),y) -> concat_1(y)
r4: app(cons_0(),y) -> cons_1(y)
r5: app(cons_1(x1),y) -> cons_2(x1,y)
r6: app(flatten_0(),y) -> flatten_1(y)
r7: app(map_0(),y) -> map_1(y)
r8: app(map_1(x1),y) -> map_2(x1,y)
r9: app(node_0(),y) -> node_1(y)
r10: app(node_1(x1),y) -> node_2(x1,y)
r11: map_2(f,nil_0()) -> nil_0()
r12: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs))
r13: flatten_1(node_2(x,xs)) -> cons_2(x,concat_1(map_2(flatten_0(),xs)))
r14: concat_1(nil_0()) -> nil_0()
r15: concat_1(cons_2(x,xs)) -> append_2(x,concat_1(xs))
r16: append_2(nil_0(),xs) -> xs
r17: append_2(cons_2(x,xs),ys) -> cons_2(x,append_2(xs,ys))

The set of usable rules consists of

  (no rules)

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      matrix interpretation with standard point-wise order:
      
        carrier: N^1
        order: standard order
        interpretations:
          map_2#_A(x1,x2) = x1 + x2 + 7
          cons_2_A(x1,x2) = x1 + x2 + 6
          app#_A(x1,x2) = x1 + x2 + 7
          map_1_A(x1) = x1 + 3
          flatten_0_A() = 1
          flatten_1#_A(x1) = x1 + 2
          node_2_A(x1,x2) = x1 + x2 + 12
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        matrix interpretation with standard point-wise order:
        
          carrier: N^1
          order: standard order
          interpretations:
            map_2#_A(x1,x2) = x2
            cons_2_A(x1,x2) = x1 + x2 + 5
            app#_A(x1,x2) = x2
            map_1_A(x1) = x1 + 3
            flatten_0_A() = 1
            flatten_1#_A(x1) = x1
            node_2_A(x1,x2) = x1 + x2 + 5
            map_2#!_A(x1,x2) = 3
            cons_2!_A(x1,x2) = x1 + x2 + 2
            app#!_A(x1,x2) = 4
            map_1!_A(x1) = 1
            flatten_0!_A() = 12
            flatten_1#!_A(x1) = x1 + 13
            node_2!_A(x1,x2) = 11
  
    partial status:
  
      pi(map_2#) = []
      pi(cons_2) = [1]
      pi(app#) = []
      pi(map_1) = [1]
      pi(flatten_0) = []
      pi(flatten_1#) = []
      pi(node_2) = []

The following rules are removed:

  p1, p2, p3, p4, p5

Then no dependency pair remains.

-- Reduction pair.

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

p1: concat_1#(cons_2(x,xs)) -> concat_1#(xs)

and R consists of:

r1: app(append_0(),y) -> append_1(y)
r2: app(append_1(x1),y) -> append_2(x1,y)
r3: app(concat_0(),y) -> concat_1(y)
r4: app(cons_0(),y) -> cons_1(y)
r5: app(cons_1(x1),y) -> cons_2(x1,y)
r6: app(flatten_0(),y) -> flatten_1(y)
r7: app(map_0(),y) -> map_1(y)
r8: app(map_1(x1),y) -> map_2(x1,y)
r9: app(node_0(),y) -> node_1(y)
r10: app(node_1(x1),y) -> node_2(x1,y)
r11: map_2(f,nil_0()) -> nil_0()
r12: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs))
r13: flatten_1(node_2(x,xs)) -> cons_2(x,concat_1(map_2(flatten_0(),xs)))
r14: concat_1(nil_0()) -> nil_0()
r15: concat_1(cons_2(x,xs)) -> append_2(x,concat_1(xs))
r16: append_2(nil_0(),xs) -> xs
r17: append_2(cons_2(x,xs),ys) -> cons_2(x,append_2(xs,ys))

The set of usable rules consists of

  (no rules)

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      matrix interpretation with standard point-wise order:
      
        carrier: N^1
        order: standard order
        interpretations:
          concat_1#_A(x1) = x1
          cons_2_A(x1,x2) = x1 + x2 + 7
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        matrix interpretation with standard point-wise order:
        
          carrier: N^1
          order: standard order
          interpretations:
            concat_1#_A(x1) = x1
            cons_2_A(x1,x2) = x1 + x2 + 9
            concat_1#!_A(x1) = x1 + 6
            cons_2!_A(x1,x2) = x1 + x2 + 5
  
    partial status:
  
      pi(concat_1#) = [1]
      pi(cons_2) = []

The following rules are removed:

  p1

Then no dependency pair remains.

-- Reduction pair.

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

p1: append_2#(cons_2(x,xs),ys) -> append_2#(xs,ys)

and R consists of:

r1: app(append_0(),y) -> append_1(y)
r2: app(append_1(x1),y) -> append_2(x1,y)
r3: app(concat_0(),y) -> concat_1(y)
r4: app(cons_0(),y) -> cons_1(y)
r5: app(cons_1(x1),y) -> cons_2(x1,y)
r6: app(flatten_0(),y) -> flatten_1(y)
r7: app(map_0(),y) -> map_1(y)
r8: app(map_1(x1),y) -> map_2(x1,y)
r9: app(node_0(),y) -> node_1(y)
r10: app(node_1(x1),y) -> node_2(x1,y)
r11: map_2(f,nil_0()) -> nil_0()
r12: map_2(f,cons_2(x,xs)) -> cons_2(app(f,x),map_2(f,xs))
r13: flatten_1(node_2(x,xs)) -> cons_2(x,concat_1(map_2(flatten_0(),xs)))
r14: concat_1(nil_0()) -> nil_0()
r15: concat_1(cons_2(x,xs)) -> append_2(x,concat_1(xs))
r16: append_2(nil_0(),xs) -> xs
r17: append_2(cons_2(x,xs),ys) -> cons_2(x,append_2(xs,ys))

The set of usable rules consists of

  (no rules)

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      matrix interpretation with standard point-wise order:
      
        carrier: N^1
        order: standard order
        interpretations:
          append_2#_A(x1,x2) = x2 + 5
          cons_2_A(x1,x2) = x1 + 4
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        matrix interpretation with standard point-wise order:
        
          carrier: N^1
          order: standard order
          interpretations:
            append_2#_A(x1,x2) = x1
            cons_2_A(x1,x2) = x1 + x2 + 5
            append_2#!_A(x1,x2) = x1 + 6
            cons_2!_A(x1,x2) = x1 + x2 + 5
  
    partial status:
  
      pi(append_2#) = [2]
      pi(cons_2) = []

The following rules are removed:

  p1

Then no dependency pair remains.