YES
We show the termination of the TRS R:

  le(|0|(),y) -> true()
  le(s(x),|0|()) -> false()
  le(s(x),s(y)) -> le(x,y)
  pred(s(x)) -> x
  minus(x,|0|()) -> x
  minus(x,s(y)) -> pred(minus(x,y))
  gcd(|0|(),y) -> y
  gcd(s(x),|0|()) -> s(x)
  gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
  if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
  if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))


-- SCC decomposition.

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

p1: le#(s(x),s(y)) -> le#(x,y)
p2: minus#(x,s(y)) -> pred#(minus(x,y))
p3: minus#(x,s(y)) -> minus#(x,y)
p4: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y))
p5: gcd#(s(x),s(y)) -> le#(y,x)
p6: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y))
p7: if_gcd#(true(),s(x),s(y)) -> minus#(x,y)
p8: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x))
p9: if_gcd#(false(),s(x),s(y)) -> minus#(y,x)

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The estimated dependency graph contains the following SCCs:

  {p4, p6, p8}
  {p1}
  {p3}


-- Reduction pair.

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

p1: if_gcd#(false(),s(x),s(y)) -> gcd#(minus(y,x),s(x))
p2: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y))
p3: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y))

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The set of usable rules consists of

  r1, r2, r3, r4, r5, r6

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      max/plus interpretation on natural numbers:
      
        if_gcd#_A(x1,x2,x3) = max{35, x1 - 1, x2, x3 - 18}
        false_A = 21
        s_A(x1) = x1 + 34
        gcd#_A(x1,x2) = max{15, x1 + 1, x2 - 18}
        minus_A(x1,x2) = max{11, x1 + 10}
        le_A(x1,x2) = max{20, x1 - 9}
        true_A = 14
        |0|_A = 22
        pred_A(x1) = max{9, x1 - 10}
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        max/plus interpretation on natural numbers:
        
          if_gcd#_A(x1,x2,x3) = 1
          false_A = 12
          s_A(x1) = max{20, x1 + 14}
          gcd#_A(x1,x2) = 1
          minus_A(x1,x2) = max{26, x1 + 12}
          le_A(x1,x2) = max{3, x1 - 3}
          true_A = 0
          |0|_A = 2
          pred_A(x1) = max{13, x1 - 14}
          if_gcd#!_A(x1,x2,x3) = max{0, x1 - 11, x3 - 21}
          false!_A = 11
          s!_A(x1) = 15
          gcd#!_A(x1,x2) = max{0, x2 - 21}
          minus!_A(x1,x2) = 0
          le!_A(x1,x2) = max{12, x1 - 1, x2 + 1}
          true!_A = 13
          |0|!_A = 14
          pred!_A(x1) = max{1, x1 - 27}
  
    partial status:
  
      pi(if_gcd#) = [2]
      pi(false) = []
      pi(s) = [1]
      pi(gcd#) = [1]
      pi(minus) = []
      pi(le) = []
      pi(true) = []
      pi(|0|) = []
      pi(pred) = []

The following rules are removed:

  p1



-- SCC decomposition.

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

p1: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y))
p2: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y))

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The estimated dependency graph contains the following SCCs:

  {p1, p2}


-- Reduction pair.

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

p1: gcd#(s(x),s(y)) -> if_gcd#(le(y,x),s(x),s(y))
p2: if_gcd#(true(),s(x),s(y)) -> gcd#(minus(x,y),s(y))

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The set of usable rules consists of

  r1, r2, r3, r4, r5, r6

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      max/plus interpretation on natural numbers:
      
        gcd#_A(x1,x2) = x1 + 2
        s_A(x1) = x1 + 17
        if_gcd#_A(x1,x2,x3) = x2 + 1
        le_A(x1,x2) = 8
        true_A = 3
        minus_A(x1,x2) = max{14, x1 + 1}
        |0|_A = 18
        false_A = 1
        pred_A(x1) = max{9, x1 - 15}
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        max/plus interpretation on natural numbers:
        
          gcd#_A(x1,x2) = max{0, x1 - 36, x2 - 38}
          s_A(x1) = max{30, x1 + 28}
          if_gcd#_A(x1,x2,x3) = max{0, x1 - 33, x2 - 39, x3 - 38}
          le_A(x1,x2) = max{x1 - 40, x2 + 20}
          true_A = 24
          minus_A(x1,x2) = max{35, x1 + 7, x2 - 31}
          |0|_A = 64
          false_A = 0
          pred_A(x1) = max{8, x1 - 28}
          gcd#!_A(x1,x2) = max{1, x1 - 9}
          s!_A(x1) = max{22, x1 + 3}
          if_gcd#!_A(x1,x2,x3) = max{2, x1 - 1, x3 - 68}
          le!_A(x1,x2) = max{18, x2 - 65}
          true!_A = 25
          minus!_A(x1,x2) = max{24, x1 - 1, x2 - 26}
          |0|!_A = 26
          false!_A = 17
          pred!_A(x1) = max{23, x1 - 34}
  
    partial status:
  
      pi(gcd#) = []
      pi(s) = []
      pi(if_gcd#) = [2]
      pi(le) = []
      pi(true) = []
      pi(minus) = []
      pi(|0|) = []
      pi(false) = []
      pi(pred) = []

The following rules are removed:

  p1, p2

Then no dependency pair remains.

-- Reduction pair.

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

p1: le#(s(x),s(y)) -> le#(x,y)

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The set of usable rules consists of

  r1

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      max/plus interpretation on natural numbers:
      
        le#_A(x1,x2) = 0
        s_A(x1) = max{3, x1 - 12}
        le_A(x1,x2) = max{4, x1 - 18, x2 - 4}
        |0|_A = 2
        true_A = 1
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        max/plus interpretation on natural numbers:
        
          le#_A(x1,x2) = max{x1, x2}
          s_A(x1) = max{19, x1 + 4}
          le_A(x1,x2) = max{14, x1 - 20, x2 - 1}
          |0|_A = 0
          true_A = 0
          le#!_A(x1,x2) = max{4, x1 - 5, x2 - 51}
          s!_A(x1) = max{3, x1 - 50}
          le!_A(x1,x2) = max{4, x1 - 68, x2 - 36}
          |0|!_A = 2
          true!_A = 1
  
    partial status:
  
      pi(le#) = []
      pi(s) = []
      pi(le) = []
      pi(|0|) = []
      pi(true) = []

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: minus#(x,s(y)) -> minus#(x,y)

and R consists of:

r1: le(|0|(),y) -> true()
r2: le(s(x),|0|()) -> false()
r3: le(s(x),s(y)) -> le(x,y)
r4: pred(s(x)) -> x
r5: minus(x,|0|()) -> x
r6: minus(x,s(y)) -> pred(minus(x,y))
r7: gcd(|0|(),y) -> y
r8: gcd(s(x),|0|()) -> s(x)
r9: gcd(s(x),s(y)) -> if_gcd(le(y,x),s(x),s(y))
r10: if_gcd(true(),s(x),s(y)) -> gcd(minus(x,y),s(y))
r11: if_gcd(false(),s(x),s(y)) -> gcd(minus(y,x),s(x))

The set of usable rules consists of

  r1, r2

Take the reduction pair:

  generalized weighted path order (>=MG, >G)
  
    base order 1:
  
      max/plus interpretation on natural numbers:
      
        minus#_A(x1,x2) = x1
        s_A(x1) = max{5, x1 - 10}
        le_A(x1,x2) = max{2, x1 - 24, x2 - 22}
        |0|_A = 4
        true_A = 1
        false_A = 1
  
    base order 2:
  
      marked-algebra reduction triple (>=A, >=A!, >A!):
      
        max/plus interpretation on natural numbers:
        
          minus#_A(x1,x2) = x2
          s_A(x1) = max{25, x1 + 6}
          le_A(x1,x2) = max{18, x1 - 26, x2 - 1}
          |0|_A = 0
          true_A = 0
          false_A = 0
          minus#!_A(x1,x2) = max{4, x2 - 1}
          s!_A(x1) = max{3, x1 - 48}
          le!_A(x1,x2) = max{2, x1 - 47, x2 - 47}
          |0|!_A = 2
          true!_A = 1
          false!_A = 1
  
    partial status:
  
      pi(minus#) = [1]
      pi(s) = []
      pi(le) = []
      pi(|0|) = []
      pi(true) = []
      pi(false) = []

The following rules are removed:

  p1

Then no dependency pair remains.