Re: Objects and Relations
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sat, 17 Feb 2007 21:14:16 GMT
Message-ID: <IeKBh.7723$R71.117631_at_ursa-nb00s0.nbnet.nb.ca>
>> On Feb 16, 4:40 am, Joe Thurbon <use..._at_thurbon.com> wrote:
>>
>>> David BL wrote:
>>>
>>> [...]
>>>
>>> PMFJI, but I think there is an essentially definitional misunderstanding
>>> here. Although, you know, I'm only new at this, so take it with a grain
>>> of salt. I'm really interrupting to see if I'm getting a better
>>> understanding of all this, and I do so with some trepidation.
>>>
>>> The word that I think is being used extremely loosely is 'entity'.
>>>
>>> In your post you use it to describe, variously,
>>>
>>> - integers,
>>> - relations,
>>> - elements of any set,
>>> - things that we want to model with a relational theory*
>>>
>>> and a term that can be used to describe anything is basically useless.
>>>
>>> *BTW, I'm using theory here in the sense of a logical theory, i.e. a set
>>> of constants, functions, domains, etc. In this post, I'll not use theory
>>> in any other sense.
>>>
>>> I'm pretty sure that Jim is using 'entity' to describe 'things that we
>>> might agree exist in the real world', or at least, things outside the
>>> relational theory at hand. An in particular, I think that things that
>>> exist within the theory are not entities, by definition.
>>>
>>> Although Jim should feel free to correct me if I'm putting words into
>>> his mouth.
>>
>>
>>
>> No you are pretty much on the money there imo Joe.
>>
>> I am happy to put up with the definition of an entity describing a set
>> of attributes/value pairs. All I object to is the concept that these
>> sets are anything but arbitrary collections.
>>
>> To some people a 'book' requires an attribute stating whether it is a
>> hardback or a softback. In other contexts a book might just be
>> composed of its title, its content, etc. (a book published online
>> perhaps). Please don't dwell on this example, it is just off the top
>> of my head to show that 'entities' are artifices and vary incredibly
>> from person to person and context to context. So as far as data
>> management is concerned, keep 'entities' out, and let humans resolve
>> such concepts outside of the logical model.
>>
>>
>>>
>>>
>>>> The word "exists" appears a lot in mathematics. For example consider
>>>
>>>
>>>> P = there exists nonzero integers x,y,z such that x^2 + y^2 = z^2
>>>
>>>
>>> Loosely, I think that P should be understood as a sentence in a formal
>>> system; one that has a fixed interpretation. In particular, the
>>> interpretation of terms like 'integers', '^', '+' etc, are all fixed
>>> within that formal system. So, 'integers' within the theory would
>>> contain constants like '0', '1' and '2' (which are also within the
>>> theory) that are intended to represent zero, one, two (which are more
>>> nebulous things (possibly entities) that exist outside the theory).
>>>
>>> For the theory to be considered good, we'd like those constants to have
>>> provable properties which accord with observable phenomena, like 'I have
>>> one apple, and give you one apple, how many apples do I have?'. My
>>> observation says I have zero apples, and my theory says I have '0'
>>> apples. Phew, my interpretation maps from '0' to zero, so my theory
>>> is good.
>>>
>>> However, it is important to note that there is no interpretation defined
>>> within a relational theory. So, any interpretation (for example from the
>>> string "12345" within the theory to my particular tax file number)
>>> necessarily happens outside the relational model. In that sense,
>>> entities play no role within a relational theory. And even more
>>> particularly, there is no requirement that things within the theory are
>>> interpreted at all. That is, you can have a relational theory which does
>>> not require you to believe in entities at all.
>>>
>>> I think the cornerstone of this misunderstanding is that you have been
>>> using the term entities to describe both things outside and things
>>> inside a relational theory. I'm pretty sure that's not the standard
>>> convention, at least within comp.databases.theory.
>>>
>>>
>>>> Generally speaking mathematicians don't waste time arging about
>>>> whether the integers exist. Instead they assume it,
>>>
>>>
>>> I normally wouldn't quibble with this terminology, but to prove a
>>> sentence like 'P' above, mathematicians only assume integers exist in as
>>> much as they are defined within the formal system in which the proof of
>>> P is going to be carried out. They don't really care if one and two
>>> exist, only '1' and '2'.
>>>
>>>
>>>> and ask more
>>>> refined questions about existence like the one above. In this case P
>>>> is true.
>>>
>>>
>>>> Now if one believes that the integers don't exist at all then clearly
>>>> P will be false.
>>>
>>>
>>> If integers don't exist within the formal system above, P is not even
>>> well formed. If integers don't exist outside the formal system above,
>>> then it has not bearing on P's truth or falsehood within the system.
>>>
>>>
>>>> Is such a philosophical position tenable for a
>>>> mathematican? No! This makes me think mathematicians have a Platonic
>>>> view whether they admit it or not.
>>>
>>>
>>> I don't think it's relevant.
>>>
>>> [... Rest snipped ... ]
>>>
>>> As I said above, I'm pretty new at the relational model stuff. I'd be
>>> interested in feedback.
>>>
>>> Cheers,
>>> Joe
>>
Date: Sat, 17 Feb 2007 21:14:16 GMT
Message-ID: <IeKBh.7723$R71.117631_at_ursa-nb00s0.nbnet.nb.ca>
> JOG wrote: >
>> On Feb 16, 4:40 am, Joe Thurbon <use..._at_thurbon.com> wrote:
>>
>>> David BL wrote:
>>>
>>> [...]
>>>
>>> PMFJI, but I think there is an essentially definitional misunderstanding
>>> here. Although, you know, I'm only new at this, so take it with a grain
>>> of salt. I'm really interrupting to see if I'm getting a better
>>> understanding of all this, and I do so with some trepidation.
>>>
>>> The word that I think is being used extremely loosely is 'entity'.
>>>
>>> In your post you use it to describe, variously,
>>>
>>> - integers,
>>> - relations,
>>> - elements of any set,
>>> - things that we want to model with a relational theory*
>>>
>>> and a term that can be used to describe anything is basically useless.
>>>
>>> *BTW, I'm using theory here in the sense of a logical theory, i.e. a set
>>> of constants, functions, domains, etc. In this post, I'll not use theory
>>> in any other sense.
>>>
>>> I'm pretty sure that Jim is using 'entity' to describe 'things that we
>>> might agree exist in the real world', or at least, things outside the
>>> relational theory at hand. An in particular, I think that things that
>>> exist within the theory are not entities, by definition.
>>>
>>> Although Jim should feel free to correct me if I'm putting words into
>>> his mouth.
>>
>>
>>
>> No you are pretty much on the money there imo Joe.
>>
>> I am happy to put up with the definition of an entity describing a set
>> of attributes/value pairs. All I object to is the concept that these
>> sets are anything but arbitrary collections.
>>
>> To some people a 'book' requires an attribute stating whether it is a
>> hardback or a softback. In other contexts a book might just be
>> composed of its title, its content, etc. (a book published online
>> perhaps). Please don't dwell on this example, it is just off the top
>> of my head to show that 'entities' are artifices and vary incredibly
>> from person to person and context to context. So as far as data
>> management is concerned, keep 'entities' out, and let humans resolve
>> such concepts outside of the logical model.
>>
>>
>>>
>>>
>>>> The word "exists" appears a lot in mathematics. For example consider
>>>
>>>
>>>> P = there exists nonzero integers x,y,z such that x^2 + y^2 = z^2
>>>
>>>
>>> Loosely, I think that P should be understood as a sentence in a formal
>>> system; one that has a fixed interpretation. In particular, the
>>> interpretation of terms like 'integers', '^', '+' etc, are all fixed
>>> within that formal system. So, 'integers' within the theory would
>>> contain constants like '0', '1' and '2' (which are also within the
>>> theory) that are intended to represent zero, one, two (which are more
>>> nebulous things (possibly entities) that exist outside the theory).
>>>
>>> For the theory to be considered good, we'd like those constants to have
>>> provable properties which accord with observable phenomena, like 'I have
>>> one apple, and give you one apple, how many apples do I have?'. My
>>> observation says I have zero apples, and my theory says I have '0'
>>> apples. Phew, my interpretation maps from '0' to zero, so my theory
>>> is good.
>>>
>>> However, it is important to note that there is no interpretation defined
>>> within a relational theory. So, any interpretation (for example from the
>>> string "12345" within the theory to my particular tax file number)
>>> necessarily happens outside the relational model. In that sense,
>>> entities play no role within a relational theory. And even more
>>> particularly, there is no requirement that things within the theory are
>>> interpreted at all. That is, you can have a relational theory which does
>>> not require you to believe in entities at all.
>>>
>>> I think the cornerstone of this misunderstanding is that you have been
>>> using the term entities to describe both things outside and things
>>> inside a relational theory. I'm pretty sure that's not the standard
>>> convention, at least within comp.databases.theory.
>>>
>>>
>>>> Generally speaking mathematicians don't waste time arging about
>>>> whether the integers exist. Instead they assume it,
>>>
>>>
>>> I normally wouldn't quibble with this terminology, but to prove a
>>> sentence like 'P' above, mathematicians only assume integers exist in as
>>> much as they are defined within the formal system in which the proof of
>>> P is going to be carried out. They don't really care if one and two
>>> exist, only '1' and '2'.
>>>
>>>
>>>> and ask more
>>>> refined questions about existence like the one above. In this case P
>>>> is true.
>>>
>>>
>>>> Now if one believes that the integers don't exist at all then clearly
>>>> P will be false.
>>>
>>>
>>> If integers don't exist within the formal system above, P is not even
>>> well formed. If integers don't exist outside the formal system above,
>>> then it has not bearing on P's truth or falsehood within the system.
>>>
>>>
>>>> Is such a philosophical position tenable for a
>>>> mathematican? No! This makes me think mathematicians have a Platonic
>>>> view whether they admit it or not.
>>>
>>>
>>> I don't think it's relevant.
>>>
>>> [... Rest snipped ... ]
>>>
>>> As I said above, I'm pretty new at the relational model stuff. I'd be
>>> interested in feedback.
>>>
>>> Cheers,
>>> Joe
>>
> Nobody asked me, but I think everybody should agree to stop this thread > as it gets into matters which humans are obviously incapable of. (Being > as religious as they seem to be, it amazes me how some posters can > persist in such arrogance, and me being rather atheistic, I think I > qualify as objective in this case.)
True objectivity demands agnosticism in the absense of empirical evidence.
> Although I don't feel capable of re-phrasing everything JOG and Joe T > have said, I think they understand the essential ingredient for using a > db for recording, abstraction. Really not a new idea, an Anglo > renaissance philosopher, John something or other, talked about it > (sorry, I forget his surname). It seems some people will never get this > as long as they live (which I think is okay as they will eventually > desist). What we express via a computer is never real because we agree > to conditions that allow us to suspend certain details in order to have > a common abstraction or metaphor. The introduction of the very word > "entity" thirty or so years ago was a most unfortunnate event. After > all that time, there has been no mechanistic theory to justify it, just > various mumbo-jumbo that appeals to emotion/wishing or involves word > games. It seems that some people can never get this. I say fine, > recognizing that could help the rest of us save time. A comparison that > makes sense to me has to do with electrons. I've been taught in several > courses that in an electrical circuit they are capable of moving long > distances. I've never been able to believe this, but at the same time > have been able to explain circuits to myself as abstractions where the > end result can be produced by imagining that they move over long > distances rather than just bounce against each other. I wish the > "real-world-entity" people would try to explain how a finite machine > could identify every electron in the world when it would have to record > its own electrons as well. Whereas what's in our heads has no such > limits and as long as we agree on some limited and coherent definition > of the symbols we want to talk about, we can mimic a fraction of our > logic on a digital computer and find that the conclusions we can come up > with in our heads seem to hold true for the computer result. We seem > to base this faith on induction. > > When I see a lot of posts on a thread that I don't understand, one > litmus test I (usually) apply is to ignore it if I see a lot of posts > from those people who seem to have been born without the abstraction dna > gene or molecule or whatever it's called. Not to say they are deficient > in every way, after all I'm deficient in lots of ways as I'm regularly > told outside of c.d.t.m but their "abstract values" are just as > mathematical sets as the ones we try to record with db's. Like all > members of sets, they can't identify themselves without outside help, > but some of the rest of us think we can identify them. That's life and > nature, we are what we are and can't change it.
Are you suggesting perhaps we could benefit from accepting what we cannot change? Received on Sat Feb 17 2007 - 22:14:16 CET