Re: What is the Venn diagram for XPath, XQuery, and X

Michele, Roger and XSL-List,

We could ask a bot to draw us an SVG and watch it lie like a dog. (A happy dog
but still a dog.)

One key to understanding the subtlety of the question is that XPath and XQuery
have both syntactic and semantic aspects. So for example we have a situation
where XPath 2.0 is a clean superset of XPath 1.0 (or pretty close to clean -
others will correct me), while with respect to the underlying semantics, XPath
2.0 is quite a different beast.

Incidentally, XQuery 1.0 is not aligned with XPath 1.0 this way - it's aligned
with XPath 2.0.

Indeed as Martin says the 'superset/subset' idea is misleading. Adding
features ordinarily means adding syntax. So the new language is a superset.
But it also means adding rules, thereby invalidating some inputs or creating
new error conditions. Semantically, the new language might thus be a subset,
except for the new features, where it's a superset.

Compatibility generally means both the syntax works, and it works the same way
- so alignment in both syntax and semantics is necessary.

This makes it an easy question to pose but difficult to answer.

What's amazing is that with respect to syntax, and modulo details about entity
resolution, the progression is pretty smooth, even while semantics and data
model develop in a big way.

Cheers, Wendell

From: Michele R Combs mrrothen@xxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Wednesday, February 1, 2023 10:44 AM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re:  What is the Venn diagram for XPath, XQuery, and XQuery
Update?

But where is the actual diagram?  :)

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From: "Joe Wicentowski joewiz@xxxxxxxxx<mailto:joewiz@xxxxxxxxx>"
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rytech.com>>
Sent: Wednesday, February 1, 2023 8:55 AM
To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx<mailto:xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re:  What is the Venn diagram for XPath, XQuery, and XQuery
Update?

Hi Roger,

I posted an answer to the question you cross-posted to Stack Overflow:

  https://stackoverflow.com/questions/75311657/what-is-the-venn-diagram-for-x
path-xquery-and-xquery-update<https://gcc02.safelinks.protection.outlook.com/
?url=https%3A%2F%2Fstackoverflow.com%2Fquestions%2F75311657%2Fwhat-is-the-ven
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Joe

On Wed, Feb 1, 2023 at 8:04 AM Roger L Costello
costello@xxxxxxxxx<mailto:costello@xxxxxxxxx>
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx<mailto:xsl-list-service@xxxxxxxxxxxx
rytech.com>> wrote:
Hi Folks,

Note: in all of the following, when I refer to "XQuery" I mean the latest
version of XQuery. Ditto for XQuery Update.

[True or False] XQuery is a superset of XPath. That is, the XQuery language
consists of all the stuff in XPath plus more.

Eek! I didn't specify the version of XPath.

[True or False] XQuery is a superset of XPath 1.0
[True or False] XQuery is a superset of XPath 2.0
[True or False] XQuery is a superset of XPath 3.0
[True or False] XQuery is a superset of XPath 3.1

[True or False] XQuery Update is a superset of XQuery.

/Roger

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