Account Options

  1. Sign in
The old Google Groups will be going away soon, but your browser is incompatible with the new version.
Google Groups Home
« Groups Home
Message from discussion chwistek and tarski on nonlogical symbols [can argt erros]
The group you are posting to is a Usenet group. Messages posted to this group will make your email address visible to anyone on the Internet.
Your reply message has not been sent.
Your post was successful
 
From:
To:
Cc:
Followup To:
Add Cc | Add Followup-to | Edit Subject
Subject:
Validation:
For verification purposes please type the characters you see in the picture below or the numbers you hear by clicking the accessibility icon. Listen and type the numbers you hear
 
Nam Nguyen  
View profile  
 More options Jun 19 2009, 12:40 am
Newsgroups: sci.logic, sci.math
From: Nam Nguyen <namducngu...@shaw.ca>
Date: Thu, 18 Jun 2009 22:40:58 -0600
Local: Fri, Jun 19 2009 12:40 am
Subject: Re: chwistek and tarski on nonlogical symbols [can argt erros]

herbzet wrote:

> Nam Nguyen wrote:
>> Jesse F. Hughes wrote:
>>> MoeBlee <jazzm...@hotmail.com> writes:
>>>> On Jun 16, 8:32 pm, Nam Nguyen <namducngu...@shaw.ca> wrote:

>>>>> Basically my claim is:

>>>>> Given a formal system T, the set of T's theorems can *not* contain more
>>>>> non-logical symbols than that of T's axiom-set.
>> MoeBlee wrote:
>>>> If the system uses logical axioms, then I don't see how the above
>>>> could be incorrect.
>> Ok. But hoe does this relate to my claim above which is *general*?
>> What did he try to say here: a refute, or a support to my claim?

>>> It could be incorrect, depending on the exact specification of the
>>> logical axioms and rules of inference, right?  In the most trivial
>>> case, we may treat all of the usual axioms as zero-ary inference
>>> rules.

>>> But I assume that Nam meant "T's *non-logical* axiom-set" in any
>>> case.  Perhaps he can clarify what he meant to say?
>> My claim says exactly what we saw above there. T's axiom-set is the
>> set of T's axioms, nothing more nothing less. Because FOL= is assumed,
>> this axiom-set will be non-empty (since x=x is in it). Would this axiom-
>> set have any non-logical symbol? My claim doesn't say; but nonetheless
>> it's still the set of axiom of T! Likewise, the set of T's theorems
>> is just that: the set of T's theorems!

>> So my claim is a very simple meta statement that's either true or false
>> but there's nothing mysterious or hard to understand what it says.

>> But it's ok to me that you asked for clarification. And I've clarified
>> it.

> I haven't been following this thread closely, just dipping into it
> from time to time, but it appears to me, that (with the the exception
> of one small point, treated below) with this post you have established
> your point beyond contention, as irreducibly and trivially true.

> Congratulations to you, and to Moeblee also, for putting his finger
> on the significant point, that the axiom set necessarily includes
> the set of logical axioms.

> The only remaining quibble is the point Jesse Helms raises.  FOL
> can be treated as an axiomless system, consisting only of a set
> of rules for transforming one string into another.  You state
> above that for FOL= there is at least one axiom, x = x.

> I am insufficiently interested in FOL= to know whether it can
> also be treated as an axiomless system.

That's not true: axiom is a formula and x=x is a formula (as I've alluded
to in my other post). So technical any formal system in FOL= can't be
an axiom-less system.

--
"To discover the proper approach to mathematical logic,
we must therefore examine the methods of the mathematician."
(Shoenfield, "Mathematical Logic")


 
You must Sign in before you can post messages.
To post a message you must first join this group.
Please update your nickname on the subscription settings page before posting.
You do not have the permission required to post.