Certification Problem

Input (TPDB TRS_Standard/AProVE_07/wiehe09)

The rewrite relation of the following TRS is considered.

Property / Task

Answer / Result

Proof (by AProVE @ termCOMP 2023)

1 Dependency Pair Transformation

1.1 Dependency Graph Processor

The dependency pairs are split into 4 components.

• The 1^st component contains the pair

  quot#(s(x),s(y))

  →

  quot#(minus(x,y),s(y))

  (18)

  1.1.1 Reduction Pair Processor with Usable Rules

  Using the Knuth Bendix order with w0 = 1 and the following precedence and weight functions

  prec(s)

  =

  0

  weight(s)

  =

  1

  in combination with the following argument filter

  π(quot#)	=	1
  π(s)	=	[1]
  π(minus)	=	1

  together with the usable rules

  minus(x,0)	→	x	(1)
  minus(minus(x,y),z)	→	minus(x,plus(y,z))	(5)
  minus(s(x),s(y))	→	minus(x,y)	(2)

  (w.r.t. the implicit argument filter of the reduction pair), the pair

  quot#(s(x),s(y))

  →

  quot#(minus(x,y),s(y))

  (18)

  could be deleted.

  1.1.1.1 P is empty

  There are no pairs anymore.

• The 2^nd component contains the pair

  minus#(minus(x,y),z)	→	minus#(x,plus(y,z))	(20)
  minus#(s(x),s(y))	→	minus#(x,y)	(17)

  1.1.2 Size-Change Termination

  Using size-change termination in combination with the subterm criterion one obtains the following initial size-change graphs.

  minus#(minus(x,y),z)	→	minus#(x,plus(y,z))	(20)
  1	>	1
  minus#(s(x),s(y))	→	minus#(x,y)	(17)
  1	>	1
  2	>	2

  As there is no critical graph in the transitive closure, there are no infinite chains.

• The 3^rd component contains the pair

  plus#(s(x),x)	→	plus#(if(gt(x,x),id(x),id(x)),s(x))	(29)
  plus#(s(x),s(y))	→	plus#(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y)))	(22)
  plus#(id(x),s(y))	→	plus#(x,if(gt(s(y),y),y,s(y)))	(33)

  1.1.3 Reduction Pair Processor with Usable Rules

  Using the matrix interpretations of dimension 1 with strict dimension 1 over the arctic semiring over the naturals

  [plus#(x1, x2)]	=	0 + 1 · x1 + 0 · x2
  [s(x1)]	=	0 + 4 · x1
  [if(x1, x2, x3)]	=	-∞ + 0 · x1 + 0 · x2 + 0 · x3
  [gt(x1, x2)]	=	-∞ + 0 · x1 + 0 · x2
  [id(x1)]	=	-∞ + 0 · x1
  [not(x1)]	=	1 + 4 · x1
  [zero]	=	1
  [true]	=	0
  [false]	=	0

  together with the usable rules

  gt(s(x),zero)	→	true	(14)
  gt(zero,y)	→	false	(15)
  gt(s(x),s(y))	→	gt(x,y)	(16)
  id(x)	→	x	(10)
  if(true,x,y)	→	x	(11)
  if(false,x,y)	→	y	(12)
  not(x)	→	if(x,false,true)	(13)

  (w.r.t. the implicit argument filter of the reduction pair), the pair

  plus#(s(x),x)

  →

  plus#(if(gt(x,x),id(x),id(x)),s(x))

  (29)

  could be deleted.

  1.1.3.1 Reduction Pair Processor with Usable Rules

  Using the matrix interpretations of dimension 1 with strict dimension 1 over the arctic semiring over the naturals

  [plus#(x1, x2)]	=	0 + 1 · x1 + 0 · x2
  [s(x1)]	=	0 + 2 · x1
  [if(x1, x2, x3)]	=	-∞ + -∞ · x1 + 0 · x2 + 0 · x3
  [gt(x1, x2)]	=	-∞ + 0 · x1 + 1 · x2
  [not(x1)]	=	4 + 2 · x1
  [id(x1)]	=	-∞ + 1 · x1
  [zero]	=	0
  [true]	=	0
  [false]	=	0

  together with the usable rules

  if(true,x,y)	→	x	(11)
  if(false,x,y)	→	y	(12)
  id(x)	→	x	(10)

  (w.r.t. the implicit argument filter of the reduction pair), the pair

  plus#(s(x),s(y))

  →

  plus#(if(gt(x,y),x,y),if(not(gt(x,y)),id(x),id(y)))

  (22)

  could be deleted.

  1.1.3.1.1 Size-Change Termination

  Using size-change termination in combination with the subterm criterion one obtains the following initial size-change graphs.

  plus#(id(x),s(y))	→	plus#(x,if(gt(s(y),y),y,s(y)))	(33)
  1	>	1

  As there is no critical graph in the transitive closure, there are no infinite chains.

• The 4^th component contains the pair

  gt#(s(x),s(y))

  →

  gt#(x,y)

  (37)

  1.1.4 Monotonic Reduction Pair Processor with Usable Rules

  Using the linear polynomial interpretation over the naturals

  [s(x1)]	=	1 · x1
  [gt#(x1, x2)]	=	1 · x1 + 1 · x2

  having no usable rules (w.r.t. the implicit argument filter of the reduction pair), the rule could be deleted.

  1.1.4.1 Size-Change Termination

  Using size-change termination in combination with the subterm criterion one obtains the following initial size-change graphs.

  gt#(s(x),s(y))	→	gt#(x,y)	(37)
  1	>	1
  2	>	2

  As there is no critical graph in the transitive closure, there are no infinite chains.