Groups | Search | Server Info | Login | Register

Groups > comp.ai.nat-lang > #2185

Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism)

From André G. Isaak <agisaak@gm.invalid>
Newsgroups comp.theory, comp.ai.philosophy, comp.ai.nat-lang, sci.lang.semantics
Subject Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism)
Date 2020-07-03 13:38 -0600
Organization Christians and Atheists United Against Creeping Agnosticism
Message-ID <rdo1ft$6rl$1@dont-email.me> (permalink)
References (18 earlier) <NLadnUYQmcdzXmPDnZ2dnUU7-TOdnZ2d@giganews.com> <rdmgi6$r2m$1@dont-email.me> <bI2dnR28Eult8mLDnZ2dnUU7-LvNnZ2d@giganews.com> <rdnv1m$mog$1@dont-email.me> <gcKdnZSGeccdHmLDnZ2dnUU7-IHNnZ2d@giganews.com>

Cross-posted to 4 groups.

Show all headers | View raw

On 2020-07-03 13:14, olcott wrote:
> On 7/3/2020 1:56 PM, André G. Isaak wrote:
>> On 2020-07-03 11:50, olcott wrote:
>>
>>> Valid in model theory and valid in deductive inference have two 
>>> distinctly different meanings.
>>>      Satisfiability
>>>      A formula is satisfiable if it is possible to find an 
>>> interpretation
>>>      (model) that makes the formula true.
>>>      https://en.wikipedia.org/wiki/Satisfiability
>>>
>>>      Interpretation (logic)
>>>      An interpretation is an assignment of meaning to the
>>>      [non-logical] symbols of a formal language.
>>>      https://en.wikipedia.org/wiki/Interpretation_(logic)
>>>
>>>      Model theory
>>>      A model of a theory is a structure (e.g. an interpretation)
>>>      that satisfies the sentences of that theory.
>>>      https://en.wikipedia.org/wiki/Model_theory
>>>
>>>      A wf B is said to be logically valid if and only if B is true
>>>      for every interpretation. (Mendelson 2015:65)
>>>
>>> Mendelson, Elliott 2015. Introduction To Mathematical Logic. Boca 
>>> Raton: CRC Press Taylor & Francis Group.
>>>
>>> A theory T is incomplete if and only if there is some sentence φ such 
>>> that (T ⊬ φ) and (T ⊬ ¬φ).
>>>
>>> This is the first time that I have every applied logical validity 
>>> within the context of symbolic logic so I may not have it correctly:
>>>
>>> It seems that within the context of: (T ⊬ φ) and (T ⊬ ¬φ) that
>>> those instances of φ in T would be defined as logically_invalid:
>>>
>>> ∀φ ∈ theory T (T ⊢ φ)  otherwise logically_invalid(T, φ)
>>> ∀φ ∈ theory T (T ⊢ ¬φ) otherwise logically_invalid(T, ¬φ)
>>>
>>> I may have this incorrectly because this is the very first time that 
>>> I applied the concept of validity within symbolic logic, but it looks 
>>> like a formal system is defined as incomplete whenever it has a WFF φ 
>>> such that Logically-Invalid(T, φ) and Logically-Invalid(T, ¬φ).
>>
>> I have no idea what you think 'invalid' means, but what you are saying 
>> above is essentially nothing unless you have some special meaning in 
>> mind.
>>
>> (A ∨ ¬A) is valid because it true on all possible interpretations.
>>
>> (A ∨ B) is not valid because it is not true on all possible 
>> interpretations. It is therefore invalid.
>>
>> You seem to want invalid to mean not-well-formed, but that isn't what 
>> it means. It simply means that there are interpretations under which 
>> something is false.
>>
>> André
>>
> 
> Semantically ill-formed.
> ("2 + 3 = 5", "5 > 3"} therefore the Sun has spots.

So according to you (A ∨ B) is 'semantically ill-formed'? In what way? 
What well-formedness rule is being violated by this?

What about x + y = y + x ? That's not provable in Q, but how exactly is 
that 'semantically ill-formed'?

What about ¬(¬A ∧ A)? That's provably true, but it involves negating a 
contradiction. According to you (¬A ∧ A) is 'semantically ill-formed' 
since it isn't provable (at least not in any consistent system given 
that it is a contradiction). But if (¬A ∧ A) is 'semantically 
ill-formed' how can we possibly negate it to get the perfectly valid 
statement ¬(¬A ∧ A)?

André

-- 
To email remove 'invalid' & replace 'gm' with well known Google mail 
service.

Back to comp.ai.nat-lang | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-26 20:03 -0500
  Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-27 11:04 -0500
  Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-27 11:14 -0500
    Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-27 11:58 -0500
      Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-27 17:09 -0500
        Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-27 20:15 -0500
        Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 olcott <NoOne@NoWhere.com> - 2020-06-28 16:32 -0500
          Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-28 21:45 -0500
            Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-28 21:27 -0600
              Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-28 21:59 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 00:48 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-28 23:57 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 13:28 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-29 12:33 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 14:33 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-29 13:52 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 15:02 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-29 14:14 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 15:39 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-29 15:13 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-29 17:09 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-29 21:21 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 01:09 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 00:24 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 16:46 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 16:46 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 18:24 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 18:15 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 19:33 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 19:18 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 20:34 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 20:06 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-06-30 21:31 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-06-30 20:54 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-01 11:03 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-01 10:35 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-01 17:35 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) Chris Buckley <alan@sabir.com> - 2020-07-01 22:47 +0000
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-02 07:01 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 10:51 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-02 10:46 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 13:59 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-02 13:37 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 09:52 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) Chris Buckley <alan@sabir.com> - 2020-07-02 15:06 +0000
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 10:56 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) Chris Buckley <alan@sabir.com> - 2020-07-02 22:52 +0000
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 18:35 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) Chris Buckley <alan@sabir.com> - 2020-07-02 23:48 +0000
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 18:57 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-02 22:03 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-02 23:13 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 00:36 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-02 23:43 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 12:50 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 12:19 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 13:21 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 12:33 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 13:48 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 13:55 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 13:06 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 13:07 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 12:56 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 14:14 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 13:38 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-03 15:59 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-03 22:54 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-04 08:56 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-04 08:12 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) olcott <NoOne@NoWhere.com> - 2020-07-04 10:06 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V13 (Isomorphism) André G. Isaak <agisaak@gm.invalid> - 2020-07-04 09:31 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V20 (Text Analysis) olcott <NoOne@NoWhere.com> - 2020-07-04 14:31 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V20 (Text Analysis) André G. Isaak <agisaak@gm.invalid> - 2020-07-04 15:17 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V20 (Text Analysis) olcott <NoOne@NoWhere.com> - 2020-07-04 17:29 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-05 13:01 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-07-05 16:40 -0700
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-05 23:52 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-07-06 00:53 -0700
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-06 10:15 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) André G. Isaak <agisaak@gm.invalid> - 2020-07-06 10:48 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) André G. Isaak <agisaak@gm.invalid> - 2020-07-06 13:55 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-07 22:13 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-07 22:44 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-06 11:49 -0500
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) André G. Isaak <agisaak@gm.invalid> - 2020-07-06 11:27 -0600
                Re: Simply defining Gödel Incompleteness and Tarski Undefinability away V23 (Newspeak) olcott <NoOne@NoWhere.com> - 2020-07-07 22:22 -0500

csiph-web