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Fixes the definition of evaluation of property path with OneOrMorePath #350

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hartig merged 3 commits into from
Jan 23, 2026
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Fixes the definition of evaluation of property path with OneOrMorePath #350

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Fixes the definition of evaluation of property path with OneOrMorePat…
hartig Jan 18, 2026
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add note about issue #349
hartig Jan 18, 2026
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hartig Jan 23, 2026
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11 changes: 9 additions & 2 deletions spec/index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -9907,6 +9907,11 @@ <h3>Property Path Patterns</h3>
</tbody>
</table>
</div>
<div class="issue" data-number="349">
The signature of `ppeval` should be extended to be:
`ppeval`(|X|, |ppe|, |Y|, |G|),
where |G| is an RDF graph.
</div>
<p>All evaluation is carried out by matching the <a href="#defn_ActiveGraph">active graph</a>
at that point in the overall query evaluation. We omit explicitly including the active graph
in each definition for clarity.</p>
Expand Down Expand Up @@ -10066,7 +10071,10 @@ <h3>Property Path Patterns</h3>
# For <a href="#defn_ppeOneOrMorePath" class="ppeOp">OneOrMorePath</a>, we take one step of the path then start
# recording nodes for results.

ppeval(<var>x</var>:term, <a href="#defn_ppeOneOrMorePath" class="ppeOp">OneOrMorePath</a>(<var>ppe</var>), <var>vy</var>:var) =
ppeval(<var>x</var>:term, <a href="#defn_ppeOneOrMorePath" class="ppeOp">OneOrMorePath</a>(<var>ppe</var>), <var>vy</var>:var) = { { (<var>vy</var>, <var>t</var>) } | <var>t</var> in <var>V</var> }
where <var>V</var> is the set of RDF terms that is returned by the
following algorithm.

Let <var>X</var> = <a href="#defn_reachableTerms"><var>reachableTerms</var></a>(<var>x</var>, <var>ppe</var>)
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@afs afs Jan 22, 2026

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Let reachableTerms(x:term, ppe) be the set of RDF terms
reached by repeated matches of ppe,
when starting at RDF term x.

"reacheable" to me means an arbitrary length match e.g. :p*

"Evaluation of OneOrMorePath" uses it as "one step".

I think the definition of reachableTerm is tying to be one step but "reachable", and "repeated matches", imply to me an arbitrary length match.

Maybe "all matches of the ppe" and maybe call it "pathMatches" or "oneStep"/"oneApplication"

"neighbors" might be possible but ppe is not just length 1.

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@hartig hartig Jan 23, 2026

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@afs I agree that this part is misleading, at best. In fact, I would say that the reachableTerms function is ill-defined. Notice, however, that this is not an issue of this PR, not even an issue of something we have done in v1.2 now. The function that is called 'reachableTerms' now was called 'eval' in 1.1 (indeed, like several other "eval" functions in 1.1)---see it being used in the definition of OneOrMorePath in 1.1 and its "definition" in the context of the ALP function in 1.1. I will open a separate issue to address this comment.

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@hartig hartig Jan 23, 2026

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Issue created: #352

Let <var>V</var> = the empty multiset
For <var>n</var> in <var>X</var>
Expand All @@ -10085,7 +10093,6 @@ <h3>Property Path Patterns</h3>
{ { } } if { (<var>vy</var>:var, <var>y</var>) } in ppeval(<var>x</var>, <a href="#defn_ppeOneOrMorePath" class="ppeOp">OneOrMorePath</a>(<var>ppe</var>), <var>vy</var>)
{ } otherwise
</pre>
<div class="issue" data-number="267"><var>V</var> is not a multiset of solution mappings but a set of RDF terms.</div>
</div>
<div class="defn">
<p><b>Definition: <span id="eval_negatedPropertySet">Evaluation of NegatedPropertySet</span></b></p>
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