RE: The limits of XML mean the limits of my data world

[Roger L Costello <costello@mitre.org>]

Peter wrote:

> overlap can be expressed but not represented

I am not clear what you mean by "overlap". Is this an example of overlap:

Classroom1 is used for teaching math, science, and writing. Classroom2 is used for teaching art, history, and writing.

There is overlap between the topics taught in classroom1 and classroom2 -- writing. Is that what you mean by "overlap"?

If so, can't that be expressed in XML something like this:

<Classrooms>
    <Classroom1>
        <ClassesTaught>
            <Class>math</Class>
            <Class>science</Class>
            <Class>writing</Class>
        </ClassesTaught>
    </Classroom1>
    <Classroom2>
        <ClassesTaught>
            <Class>art</Class>
            <Class>history</Class>
            <Class>writing</Class>
        </ClassesTaught>
    </Classroom2>
</Classrooms>

Dimitre wrote:

> XML may not be good at representing concurrency (overlap just on one-dimension -- time).

Is this an example of concurrency?

During times 1 - 3 John Doe is driving from Boston to NYC and during the same times Sally Smith is driving from LA to San Diego.

Is that an example of what you mean? If so, can't that be expressed in XML something like this:

<DrivingTrips>
    <Person>
        <Name>John Doe</Name>
        <Itinerary>
            <Start>Boston</Start>
            <End>NYC</End>
        </Itinerary>
        <DriveTimes>
            <Time1/>
            <Time2/>
            <Time3/>
        </DriveTimes>
    </Person>
    <Person>
        <Name>Sally Smith</Name>
        <Itinerary>
            <Start>LA</Start>
            <End>San Diego</End>
        </Itinerary>
        <DriveTimes>
            <Time1/>
            <Time2/>
            <Time3/>
        </DriveTimes>
    </Person>
</DrivingTrips>

Peter said:

> CSV is better at expressing row-and-column type data.

That might well be true, but it is possible to express row-and-column concepts in XML. That is, the row-and-column concept in not outside the realm of concepts expressible by the XML language.

> Various forms of database are better at expressing other layouts of atomic and relational data. 

Again, that might well be true but the concept of a table is expressible in XML.

Thank you Peter, Dimitre, and Gerrit but you haven't (yet) convinced me that there are concepts that are outside the realm of concepts expressible using the language called XML.

A friend of mine is Chinese and today I asked her: "Are there concepts that you can express in English that you cannot express in Chinese?" She responded, "Yes, there are concepts in English for which there is no equivalent in Chinese." (The reverse is also true -- there are concepts that can be expressed in Chinese that cannot be expressed in English.)

Are there concepts in data language XYZ that cannot be expressed in the data language we call XML? What are the boundaries of the language we call XML, in terms of concepts that can be expressed? How does the XML language bound (limit) ones thinking about data?

/Roger