Re: Rule of -> introduction

From: Andreas (no email)
Date: 02/26/05 

Date: Sat, 26 Feb 2005 17:50:28 +0100

On Sat, 26 Feb 2005 16:44:01 +0100, G. Frege <no_spam@aol.com> wrote:

>On Sat, 26 Feb 2005 16:01:08 +0100, Andreas <> wrote:
>
>>
>> I have a quesion concerning the rule of implication introduction (->I)
>> for NK. I know that the rule schematically is:
>>
>> j (j) p
>>
>> a1...an (k) q
>>
>> a1...an/j (m) p -> q j,k ->I
>>
>> Where the assumption number j is omitted from the set of assumption
>> numbers at line m, if it is one of them.
>>
>The formula in line (j) m u s t be an assumption. Hence it just depends on
>itself:
>
> j (j) A
>
>where j may be any number.
>
>>
>> r,o (j) p
>>
>p is obviously n o t an assumption, hence ->I doesn't apply.
>

OK, thanks very much. I figured, but I wasn't completely shure.

//Andreas.