YES

# parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023)

Consider the left-linear TRS R:

  g(a(),y) -> y
  f(x,a()) -> f(x,g(x,b()))
  g(h(x),y) -> g(x,h(y))

Let C be the following subset of R:

  g(a(),y) -> y
  g(h(x),y) -> g(x,h(y))

The TRS R is left-linear and all parallel critical pairs are joinable by C.
Therefore, the confluence of R is equivalent to that of C.

# parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023)

Consider the left-linear TRS R:

  g(a(),y) -> y
  g(h(x),y) -> g(x,h(y))

Let C be the following subset of R:

  g(h(x),y) -> g(x,h(y))

The TRS R is left-linear and all parallel critical pairs are joinable by C.
Therefore, the confluence of R is equivalent to that of C.

# parallel critical pair closing system (Shintani and Hirokawa 2022, Section 8 in LMCS 2023)

Consider the left-linear TRS R:

  g(h(x),y) -> g(x,h(y))

Let C be the following subset of R:

  (empty)

The TRS R is left-linear and all parallel critical pairs are joinable by C.
Therefore, the confluence of R is equivalent to that of C.

# emptiness

The empty TRS is confluent.