Revise RDFterm-equal and function sameTerm. Rename RDFterm-equal to sameValue. #194

afs · 2025-02-05T11:03:19Z

This closes #187.
This closes #25.

Changes:

Rename RDFterm-equal as sameValue
Reorder sameTerm, sameValue
Reword sameValue (see Refining RDFTerm-equals #187)
Bring definition/description of RDF term equality up-to-date - see related issue RDF term equality definitions rdf-concepts#154
Replace examples

Preview | Diff

afs · 2025-02-05T11:08:12Z

~~At the moment this is unfinished, work in progress.~~

It has editor's notes in the text, in a lurid colour, for further changes. These can be seen in the preview.

The diff isn't very useful except to show the changes are only in one area of the document.

cc editors of RDF Concepts -- @gkellogg @pchampin

spec/index.html

afs · 2025-02-24T16:52:59Z

There are still 4 "editors notes" for work to be done - one of them is waiting on w3c/rdf-concepts#154.

hartig · 2025-02-24T16:56:06Z

There are still 4 "editors notes" for work to be done - one of them is waiting on w3c/rdf-concepts#154.

Okay, I will work on a PR for w3c/rdf-concepts#154 right away (as PR w3c/rdf-concepts#158 is merged now).

hartig · 2025-02-25T08:47:08Z

There are still 4 "editors notes" for work to be done - one of them is waiting on w3c/rdf-concepts#154.

Okay, I will work on a PR for w3c/rdf-concepts#154 right away (as PR w3c/rdf-concepts#158 is merged now).

The PR for w3c/rdf-concepts#154 is ready; see: w3c/rdf-concepts#161

Tpt

Thank you for pushing this and for answering all my nitpicks.

I am still not convinced that the special case for NaN is worth it while sameValue is kept as only a way to define = but it's not a big deal (my bold assumption is that we will never expose sameValue directly).

afs · 2025-03-26T15:09:31Z

Bold.

😄

rubensworks

Just some minor suggestions. Looks good to me in general!

spec/index.html

afs · 2025-03-31T14:48:22Z

@kasei , @hartig

Is the current state of this PR satisfactory for merge? If so, could you approve it?

hartig · 2025-03-31T15:00:06Z

Is the current state of this PR satisfactory for merge? If so, could you approve it?

Andy, sorry for having been quiet in this PR recently. I have an important deadline tomorrow and will be able to come back to this PR only later this week.

afs · 2025-03-31T15:38:29Z

If appropriate, we can proceed by raising subsequent issues so that merge can proceed.

(for the merge, I will squash commits so we have a commit for the long term record)

kasei · 2025-04-01T14:16:49Z

@kasei , @hartig

Is the current state of this PR satisfactory for merge? If so, could you approve it?

I'll take a look today.

kasei · 2025-04-01T16:11:51Z

This looks good to me with one exception: the special handling for "NaN" in §17.4.2.2 sameValue. The content in §17.4.2.2 seems reasonable, and the rationale provided in the following NOTE section is good. However, I'm not sure how you'd ever get into sameValue when trying to evaluate something like "NaN"^^xsd:double = "NaN"^^xsd:float because §17.3 Operator Mapping seems clear that the rule for numeric types (using op:numeric-equal) would take precedence over the fallback rule for RDF terms (using sameValue).

Since this is value-specific, we can't simply add a new row to the operator mapping table, but I think something needs to be done to ensure handling of NaN values ends up using sameValue semantics rather than numeric-equal semantics.

afs · 2025-04-01T17:07:32Z

Handling NaNs (any mix double/float) will go to op:numeric-equal.

There is lots of discussion up-thread so I'll try not repeat that all.

Identity isn't equality for NaNs. https://www.w3.org/TR/xmlschema11-2/#equality

"NaN"^^xsd:double is not a consistent point-extension of the number value space R -- it's not an algebraic group under + any longer (there is no inverse). Both op:numeric-less-than(NaN, NaN) and op:numeric-greater-than(NaN, NaN) is false (numeric-greater-than is defined by argument switching, not via fn:not) and op:numeric-equal is false

In a graph matching, two uses of "NaN"^^double" are the same term.

Everywhere else, sameTerm implies sameValue because L2V is a function.

[RDF Concept 5. Datatypes] https://www.w3.org/TR/rdf12-concepts/#section-Datatypes
"Datatypes are used with RDF literals to represent values"

So there is choice here.
graph/value-motivated vs expression/F&O motivated. Two different places where identity/equality happen.

We don't need sameValue to be same as =. We can have sameValue means same element in the value space.

If RDF ever becomes value-centric, including the pattern of reading data and canonicalizing numbers on input,
sameTerm implies sameValue matters.

kasei · 2025-04-01T17:33:11Z

Sorry. I hadn't been able to follow all the discussion in the thread. Just to be clear - since sameValue isn't exposed as a callable function, is there any practical use to this definition (w.r.t. "NaN" values)? Or is it just to align with the conceptual need for "sameTerm implies sameValue"? I think it's the latter based on the comments above from @Tpt (?). If that's the case, I'm OK with this being merged, though I think it might be a point of confusion to readers of the spec in the future.

afs · 2025-04-01T18:15:21Z

is there any practical use to this definition

Currently, no - sameValue is not exposed as a callable function.

is it just to align with the conceptual need for "sameTerm implies sameValue"?

Yes.

a point of confusion to readers of the spec in the future.

Anything to do with NaNs is confusing in the details. Intuitions mislead.

kasei · 2025-04-01T22:07:56Z

Anything to do with NaNs is confusing in the details. Intuitions mislead.

Agreed. My concern is more around the fact that the document is defining behavior that can't ever be used, though (so not really about NaNs… could be about anything). I'm happy to let this get merged, but it strikes me as really strange to be adding definitions that can't possibly be used/observed in a SPARQL system. Obviously it would be different if sameValue were callable.

afs · 2025-04-02T08:12:54Z

Issue #201 for whether sameValue should be callable.

afs · 2025-04-04T14:03:27Z

Squashed authoring, editing and review commits.

TallTed · 2025-04-04T15:39:31Z

spec/index.html

+              </li>
+              <li>If <code>term1</code> and <code>term2</code> are both 
+                <a data-cite="RDF12-CONCEPTS#dfn-literal">literals</a>
+                and the SPARQL processor can determine that their the values are equal,


Suggested change

and the SPARQL processor can determine that their the values are equal,

and the SPARQL processor can determine that their values are equal,

TallTed · 2025-04-04T15:40:18Z

spec/index.html

+              </li>
+              <li>If <code>term1</code> and <code>term2</code> are both 
+                <a data-cite="RDF12-CONCEPTS#dfn-literal">literals</a>
+                and the SPARQL processor can determine the values can not be equal,


Suggested change

and the SPARQL processor can determine the values can not be equal,

and the SPARQL processor can determine that their values cannot be equal,

TallTed · 2025-04-04T15:43:46Z

spec/index.html

+                can determine that the values of these literals are equal or are not equal. 
+                If the SPARQL processor can not be sure, it returns `error`.


Suggested change

can determine that the values of these literals are equal or are not equal.

If the SPARQL processor can not be sure, it returns `error`.

can determine that the values of these literals are equal or are not equal, respectively.

If the SPARQL processor cannot be sure, it returns `error`.

afs requested review from Tpt, hartig, kasei and rubensworks February 5, 2025 11:08

afs force-pushed the rdf-term-equals branch from 108e37c to 3e4eb6c Compare February 6, 2025 10:27

Preparatory reformating

75fabc0

afs force-pushed the rdf-term-equals branch from 3e4eb6c to d07541c Compare February 13, 2025 20:22

This was referenced Feb 18, 2025

Renames 'RDFterm-equal' to 'sameValue' #197

Closed

Refining RDFTerm-equals #187

Closed

afs force-pushed the rdf-term-equals branch 7 times, most recently from a7ec54a to 5555e41 Compare February 23, 2025 17:01

GH-187: Revise RDFterm-equal; update RDF term equality

49052af

afs force-pushed the rdf-term-equals branch from 5555e41 to 49052af Compare February 23, 2025 17:06

afs marked this pull request as ready for review February 24, 2025 16:47

hartig reviewed Feb 24, 2025

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afs force-pushed the rdf-term-equals branch from 4e9e318 to 6bce77f Compare February 24, 2025 16:51

afs force-pushed the rdf-term-equals branch 3 times, most recently from 7d51235 to 156b28f Compare February 25, 2025 18:35

GH-25: Rename RDFterm-equal to sameValue

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afs force-pushed the rdf-term-equals branch from 156b28f to 85ef5b7 Compare March 1, 2025 18:55

afs force-pushed the rdf-term-equals branch 3 times, most recently from f4990ef to e305cf3 Compare March 25, 2025 20:50

Tpt approved these changes Mar 26, 2025

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afs requested review from hartig and rubensworks March 27, 2025 09:09

rubensworks approved these changes Mar 27, 2025

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kasei approved these changes Apr 1, 2025

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afs mentioned this pull request Apr 2, 2025

Should sameValue be callable? #201

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hartig approved these changes Apr 3, 2025

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afs added 2 commits April 4, 2025 15:00

Only literal sameValue can be extended

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Add = and != for IRIs, bnodes and triple terms

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afs force-pushed the rdf-term-equals branch from 04e6b6e to 0391ac4 Compare April 4, 2025 14:02

afs merged commit dc25411 into main Apr 4, 2025
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Revise RDFterm-equal and function sameTerm. Rename RDFterm-equal to sameValue. #194

Revise RDFterm-equal and function sameTerm. Rename RDFterm-equal to sameValue. #194

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	and the SPARQL processor can determine that their the values are equal,
	and the SPARQL processor can determine that their values are equal,

		can determine that the values of these literals are equal or are not equal.
		If the SPARQL processor can not be sure, it returns `error`.

Revise RDFterm-equal and function sameTerm. Rename RDFterm-equal to sameValue. #194

Revise RDFterm-equal and function sameTerm. Rename RDFterm-equal to sameValue. #194

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