well formed formulas

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well formed formulas

Postby chris12 on April 5th, 2014, 10:59 am 

Are the following formulas wff??

1)

2)
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Re: well formed formulas

Postby Hendrick Laursen on April 5th, 2014, 11:55 am 

I doubt.
Yours
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Re: well formed formulas

Postby chris12 on April 5th, 2014, 2:00 pm 



Where do you support your doubts
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Re: well formed formulas

Postby Natural ChemE on April 5th, 2014, 4:28 pm 

chris12,

We can definitely read those formulas and understand their intent, so I guess the question's whether or not they conform to a specific set of rules in one of your textbooks, right?

For the first one I'd be suspicious about the x=y=z syntax, which has four possible meanings that I can think of:
  1. and ;
  2. ;
  3. ;
  4. assign the value of z to variables x and y.
I'm not sure how it would read in Formal Logic, if at all.
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Re: well formed formulas

Postby chris12 on April 5th, 2014, 7:54 pm 

Natural ChemE » April 5th, 2014, 3:28 pm wrote:chris12,

We can definitely read those formulas and understand their intent, so I guess the question's whether or not they conform to a specific set of rules in one of your textbooks, right?

For the first one I'd be suspicious about the x=y=z syntax, which has four possible meanings that I can think of:
  1. and ;
  2. ;
  3. ;
  4. assign the value of z to variables x and y.
I'm not sure how it would read in Formal Logic, if at all.


The rules of wff are universal and do not depend on a particular book.

Now in the 2nd formula if we put x=2 and y=0 we get : (2.0=0)=> 2=1,which is a false result.

Can therefor the 2nd formula be a wff??
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Re: well formed formulas

Postby Natural ChemE on April 6th, 2014, 4:18 pm 

chris12,

As I read it, is something like, "If multiplying any number by produces , then must be one. This is true for all ."

"This is true for all ." is weird. Since the inner logic constrains to one, why go on to say "for all "?

Perhaps the grammar that you're supposed to use doesn't allow when is already constrained to a single value?

PS - Does a WFF need to be factually correct? This is, if the statement is correct grammatically but not logically, then is it still a WFF?
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