YES 0.841 H-Termination proof of /home/matraf/haskell/eval_FullyBlown_Fast/List.hs
H-Termination of the given Haskell-Program with start terms could successfully be proven:



HASKELL
  ↳ LR

mainModule List
  ((find :: (a  ->  Bool ->  [a ->  Maybe a) :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : _) Just a



Lambda Reductions:
The following Lambda expression
\vu39
case vu39 of
 x → if p x then x : [] else []
 _ → []

is transformed to
filter0 p vu39 = 
case vu39 of
 x → if p x then x : [] else []
 _ → []



↳ HASKELL
  ↳ LR
HASKELL
      ↳ CR

mainModule List
  ((find :: (a  ->  Bool ->  [a ->  Maybe a) :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : _) Just a



Case Reductions:
The following Case expression
case vu39 of
 x → if p x then x : [] else []
 _ → []

is transformed to
filter00 p x = if p x then x : [] else []
filter00 p _ = []



↳ HASKELL
  ↳ LR
    ↳ HASKELL
      ↳ CR
HASKELL
          ↳ IFR

mainModule List
  ((find :: (a  ->  Bool ->  [a ->  Maybe a) :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : _) Just a



If Reductions:
The following If expression
if p x then x : [] else []

is transformed to
filter000 x True = x : []
filter000 x False = []



↳ HASKELL
  ↳ LR
    ↳ HASKELL
      ↳ CR
        ↳ HASKELL
          ↳ IFR
HASKELL
              ↳ BR

mainModule List
  ((find :: (a  ->  Bool ->  [a ->  Maybe a) :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : _) Just a



Replaced joker patterns by fresh variables and removed binding patterns.

↳ HASKELL
  ↳ LR
    ↳ HASKELL
      ↳ CR
        ↳ HASKELL
          ↳ IFR
            ↳ HASKELL
              ↳ BR
HASKELL
                  ↳ COR

mainModule List
  ((find :: (a  ->  Bool ->  [a ->  Maybe a) :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : vwJust a



Cond Reductions:
The following Function with conditions
undefined 
 | False
 = undefined

is transformed to
undefined  = undefined1

undefined0 True = undefined

undefined1  = undefined0 False



↳ HASKELL
  ↳ LR
    ↳ HASKELL
      ↳ CR
        ↳ HASKELL
          ↳ IFR
            ↳ HASKELL
              ↳ BR
                ↳ HASKELL
                  ↳ COR
HASKELL
                      ↳ Narrow

mainModule List
  (find :: (a  ->  Bool ->  [a ->  Maybe a)

module List where
  import qualified Maybe
import qualified Prelude

  find :: (a  ->  Bool ->  [a ->  Maybe a
find p Maybe.listToMaybe . filter p


module Maybe where
  import qualified List
import qualified Prelude

  listToMaybe :: [a ->  Maybe a
listToMaybe [] Nothing
listToMaybe (a : vwJust a



Haskell To QDPs


↳ HASKELL
  ↳ LR
    ↳ HASKELL
      ↳ CR
        ↳ HASKELL
          ↳ IFR
            ↳ HASKELL
              ↳ BR
                ↳ HASKELL
                  ↳ COR
                    ↳ HASKELL
                      ↳ Narrow
QDP
                          ↳ QDPSizeChangeProof

Q DP problem:
The TRS P consists of the following rules:

new_listToMaybe0(wu3, :(wu40, wu41), ba) → new_listToMaybe(wu40, wu3, wu41, ba)
new_listToMaybe(wu40, wu3, wu41, ba) → new_listToMaybe0(wu3, wu41, ba)

R is empty.
Q is empty.
We have to consider all minimal (P,Q,R)-chains.
By using the subterm criterion [20] together with the size-change analysis [32] we have proven that there are no infinite chains for this DP problem.

From the DPs we obtained the following set of size-change graphs: