YES

TRS:

  app(app(lt(),app(s(),x)),app(s(),y)) -> app(app(lt(),x),y)
  app(app(lt(),0()),app(s(),y)) -> true()
  app(app(lt(),y),0()) -> false()
  app(app(eq(),x),x) -> true()
  app(app(eq(),app(s(),x)),0()) -> false()
  app(app(eq(),0()),app(s(),x)) -> false()
  app(app(member(),w),null()) -> false()
  app(app(member(),w),app(app(app(fork(),x),y),z)) -> app(app(app(if(),app(app(lt(),w),y)),app(app(member(),w),x)),app(app(app(if(),app(app(eq(),w),y)),true()),app(app(member(),w),z)))

max/plus interpretations on N:

  app_A(x1,x2) = max{6, -10 + x1, 9}
  app#_A(x1,x2) = max{15, 10 + x1, 14}
  lt_A = 19
  lt#_A = 4
  s_A = 12
  s#_A = 2
  0_A = 1
  0#_A = 4
  true_A = 8
  true#_A = 3
  false_A = 9
  false#_A = 1
  eq_A = 42
  eq#_A = 0
  member_A = 51
  member#_A = 5
  null_A = 1
  null#_A = 2
  fork_A = 62
  fork#_A = 6
  if_A = 40
  if#_A = 4

precedence:

  app = fork > s = member > lt = 0 = null = if > false > eq > true