[Agda] Checking termination is not sufficiently exploratory.

[Serge Leblanc]

Would an expert help me to improve the termination checking algorithm?
Does someone already work to improve the algorithm?

Ĉu spertulo bonvolus helpi min aldoni ŝanĝon al la finiĝokontrola algoritmo?
Ĉu iu jam laboras por plibonigi la algoritmon?

Sincere

 
On 2018-07-31 03:02, Serge Leblanc wrote:
> In my opinion, a normal form verification phase could be added without
> changing the termination checking algorithm.
> Laŭ mi, normala kontrola fazo povus esti aldonita sen ŝangi la finiĝan
> kontrolan algoritmon.
>
> Sincere
>
>
> On 2018-07-30 20:06, a.j.rouvoet wrote:
>>
>> I believe that you are right that the two snippets are equivalent,
>> but it requires some computation to show that this is the case.
>> The check that Agda runs on the other hand is very syntactic. This is
>> indeed a limitation, but at least it ensures that checking for
>> termination terminates ;-)
>>
>> On 07/30/2018 06:04 PM, Serge Leblanc wrote:
>>> Yes, but you translat the code (toCostring ">>") ++ coSplit "(♭ xs)
>>> to its normal form, it equals to '>' ∷ ♯ ('>' ∷ ♯ coSplit '(♭ xs)).
>>> Right?
>>> So, the recursive call is well protected by a constructor.
>>>
>>> Jes, sed vi plenumas la kodon (toCostring ">>") ++ coSplit″ (♭ xs)
>>> ĝis sia normala formo, ĝi egalas al  '>' ∷ ♯ ('>' ∷ ♯ coSplit′ (♭
>>> xs)). Ĉu ne ?
>>> Do, la memsinkceva alvoko estas bone ŝirmi per konstruisto.
>>>
>>> On 2018-07-30 16:59, a.j.rouvoet wrote:
>>>>
>>>> For coSplit to pass the checker, the recursive invocation must
>>>> appear guarded by a constructor.
>>>> This is clearly the case in coSplit', but not necessarily in
>>>> coSplit'' (e.g. when toString ">>" returns the empty costring).
>>>>
>>>>
>>>> On 07/30/2018 04:55 PM, Serge Leblanc wrote:
>>>>> Dear all,
>>>>> Why the checking termination rejects the coSplit" function
>>>>> although the coSplit' function is accepted ?
>>>>> Why the checking termination so suspicious?
>>>>> Sincerely
>>>>>
>>>>> Estimataj ĉiuj,
>>>>> Kial la finiĝa kontrolo malakceptas la funkcion coSplit″ kvankam
>>>>> la funkcio coSplit′ trafas ?
>>>>> Kial la finiĝa kontrolo estas tiel malakceptanda ?
>>>>> Sincere
>>>>>
>>>>>   coSplit′ : Costring → Costring
>>>>>   coSplit′ [] = []
>>>>>   coSplit′ (x ∷ xs) with x ≐ '!'
>>>>>   ... | false = x ∷ ♯ coSplit′ (♭ xs)
>>>>>   ... | true = '>' ∷ ♯ ('>' ∷ ♯ coSplit′ (♭ xs))
>>>>>
>>>>>   coSplit″ : Costring → Costring
>>>>>   coSplit″ [] = []
>>>>>   coSplit″ (x ∷ xs) with x ≐ '!'
>>>>>   ... | false = x ∷ ♯ coSplit″ (♭ xs)
>>>>>   ... | true = (toCostring ">>") ++ coSplit″ (♭ xs)
>>>>>
>>>>>   main = run $ ♯ getContents >>= λ s → ♯ (putStrLn∞ ∘ coSplit′) s
>>>>>
>>>>> -- 
>>>>> Serge Leblanc
>>>>> ------------------------------------------------------------------------
>>>>> gpg --search-keys 0x67B17A3F
>>>>> Fingerprint = 2B2D AC93 8620 43D3 D2C2 C2D3 B67C F631 67B1 7A3F
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Agda mailing list
>>>>> Agda at lists.chalmers.se
>>>>> https://lists.chalmers.se/mailman/listinfo/agda
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Agda mailing list
>>>> Agda at lists.chalmers.se
>>>> https://lists.chalmers.se/mailman/listinfo/agda
>>>
>>> -- 
>>> Serge Leblanc
>>> ------------------------------------------------------------------------
>>> gpg --search-keys 0x67B17A3F
>>> Fingerprint = 2B2D AC93 8620 43D3 D2C2 C2D3 B67C F631 67B1 7A3F
>>>
>>>
>>> _______________________________________________
>>> Agda mailing list
>>> Agda at lists.chalmers.se
>>> https://lists.chalmers.se/mailman/listinfo/agda
>>
>>
>>
>> _______________________________________________
>> Agda mailing list
>> Agda at lists.chalmers.se
>> https://lists.chalmers.se/mailman/listinfo/agda
>
> -- 
> Serge Leblanc
> ------------------------------------------------------------------------
> gpg --search-keys 0x67B17A3F
> Fingerprint = 2B2D AC93 8620 43D3 D2C2 C2D3 B67C F631 67B1 7A3F

-- 
Serge Leblanc
------------------------------------------------------------------------
gpg --search-keys 0x67B17A3F
Fingerprint = 2B2D AC93 8620 43D3 D2C2 C2D3 B67C F631 67B1 7A3F
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