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GH-187: Revise sameValue; produce error for 'don't know' #343

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Jan 21, 2026
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GH-187: Revise sameValue; produce error for 'don't know' #343

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118 changes: 66 additions & 52 deletions spec/index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -5978,6 +5978,9 @@ <h5>sameTerm</h5>
<section id="func-sameValue">
<span id="func-RDFterm-equal"><!-- obsolete id --></span>
<h5>sameValue</h5>
<p style="text-indent: 50px; margin-top: -5px">
<i>This function replaces</i> <code>RDFterm-equal</code> <i> from SPARQL 1.1.</i>
</p>
<pre class="prototype nohighlight">
<span class="return">xsd:boolean</span> <span class="operator" style="text-transform: none;">sameValue</span> (<span class="type"><span class="type RDFterm">RDF term</span></span> <span class="name">term1</span>, <span class="type"><span class="type RDFterm">RDF term</span></span> <span class="name">term2</span>)
</pre>
Expand All @@ -5992,21 +5995,32 @@ <h5>sameValue</h5>
<p>The result of this function is determined by going through the following steps.</p>

<ol>
<li>If <code>term1</code> and <code>term2</code> are
<li>
If <code>term1</code> and <code>term2</code> are
<a data-cite="RDF12-CONCEPTS#dfn-rdf-term-equality">equal RDF terms</a>,
then return TRUE.
</li>
<li>If <code>term1</code> or <code>term2</code> is an
<li>
If <code>term1</code> or <code>term2</code> is an
<a data-cite="RDF12-CONCEPTS#dfn-iri">IRI</a> or a
<a data-cite="RDF12-CONCEPTS#dfn-blank-node">blank node</a>
then return FALSE.
<li>If <code>term1</code> and <code>term2</code> are both
<a data-cite="RDF12-CONCEPTS#dfn-literal">literals</a>
and one or both of these literals has a datatype that is
not handled by the SPARQL processor,
then produce an [=error=].
</li>
<li>If <code>term1</code> and <code>term2</code> are both
<li>
If exactly one of <code>term1</code> and <code>term2</code> is a
<a data-cite="RDF12-CONCEPTS#dfn-triple-term">triple term</a>,
then return FALSE.
</li>
<li>
If <code>term1</code> and <code>term2</code> are both
<a data-cite="RDF12-CONCEPTS#dfn-triple-term">triple terms</a>,
apply the function `sameValue` pair-wise to each of the components.
Return TRUE if each component pair returns TRUE;
produce an [=error=] if any component pair produces an [=error=];
otherwise return FALSE.
</li>
<li>
If <code>term1</code> and <code>term2</code> are both
<a data-cite="RDF12-CONCEPTS#dfn-literal">literals</a>
and one or both of these literals are known to be
<a data-cite="RDF12-CONCEPTS#dfn-ill-typed">ill-typed</a>,
Expand All @@ -6019,41 +6033,39 @@ <h5>sameValue</h5>
both "NaN" for either xsd:double or xsd:float, then
return TRUE.
</li>
<li>If <code>term1</code> and <code>term2</code> are both
<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,
and the SPARQL processor can determine that their values are equal,
then return TRUE.
</li>
<li>If <code>term1</code> and <code>term2</code> are both
<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,
then return FALSE.
and the SPARQL processor can determine that their values
are not equal, then return FALSE.
</li>
<li>
If <code>term1</code> and <code>term2</code> are both
<a data-cite="RDF12-CONCEPTS#dfn-triple-term">triple terms</a>,
apply the function `sameValue` pair-wise to each of the components.
Return TRUE if each component pair returns TRUE;
produce an [=error=] if any component pair produces an [=error=];
otherwise return FALSE.
Otherwise, produce an [=error=].
</li>
<li>Otherwise, return FALSE.</li>
</ol>
<div id="sameValue-ill-typed" class="note">
<p>A literal is
<a data-cite="RDF12-CONCEPTS#dfn-ill-typed">ill-typed</a>
if its datatype is handled by the SPARQL processor and
its lexical form is not in the
<a data-cite="RDF12-CONCEPTS#dfn-lexical-space">lexical space</a>
of the datatype.
</p>
<p>
If the two arguments are literals, the function `sameValue`
returns `true` or `false` in cases where the SPARQL processor
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`.
</p>
</div>
<p id="sameValue-note" class="note">
If the two arguments are literals, the function `sameValue`
returns `true` or `false` in cases where the SPARQL processor
can determine that the values of these literals are equal or are not equal.
If the SPARQL processor cannot be sure, it returns `error`.
</p>
<p id="sameValue-ill-typed" class="note">
A literal is
<a data-cite="RDF12-CONCEPTS#dfn-ill-typed">ill-typed</a>
if its datatype is handled by the SPARQL processor and
its lexical form is not in the
<a data-cite="RDF12-CONCEPTS#dfn-lexical-space">lexical space</a>
of the datatype.
</p>
<p id="sameValue-zeros" class="note">
For xsd:double and xsd:float, `+0`, `-0` and `0` are same value.
</p>
<div id="sameValue-NaN" class="note">
<p>
The <a href="#OperatorMapping">Operator Mapping</a> for "`=`"
Expand All @@ -6063,24 +6075,17 @@ <h5>sameValue</h5>
However, `sameTerm("NaN"^^xsd:double, "NaN"^^xsd:double)` is true.
The function `sameValue` defines `sameValue("NaN"^^xsd:double, "NaN"^^xsd:double)`
to be true because the arguments are the same element of the value space.
Similarly, the function `sameValue` defines `sameValue("NaN"^^xsd:float, "NaN"^^xsd:float)`
to be true.

</p>
<p>
`sameValue` treats the values of `"NaN"^^xsd:double` and `"NaN"^^xsd:float` as being
the same. `sameValue("NaN"^^xsd:double, "NaN"^^xsd:float)` is `true`.
`sameValue` treats the values of `"NaN"^^xsd:double` and `"NaN"^^xsd:float`
as being the same value.
`sameValue("NaN"^^xsd:double, "NaN"^^xsd:float)` and
`sameValue("NaN"^^xsd:float, "NaN"^^xsd:double)` are both `true`.
</p>
</div>
<p id="sameValue-zeros" class="note">
For xsd:double and xsd:float, `+0`, `-0` and `0` are same value.
</p>
<p id="func-sameValue-note1" class="note">
An extended implementation may support additional datatypes for literals. An
implementation processing a query that tests for equivalence of literals with non-recognized datatypes
(and non-identical lexical form and datatype IRI) returns an error, indicating that it
is unable to determine whether or not the values of the compared literals are equivalent. For example, an
unextended implementation will produce an error when testing either <span class="queryExcerpt"><code>"iiii"^^my:romanNumeral =
"iv"^^my:romanNumeral</code></span> or <span class="queryExcerpt"><code>"iiii"^^my:romanNumeral !=
"iv"^^my:romanNumeral</code></span>.
</p>

<p>Examples:</p>
<div class="result">
Expand Down Expand Up @@ -6109,8 +6114,13 @@ <h5>sameValue</h5>
</tbody>
</table>
</div>
<p id="sameValue-old-name" class="note">
This function was called `RDFterm-equal` up until SPARQL 1.1.
<p id="func-sameValue-note1" class="note">
An extended implementation may support additional datatypes for literals. An
implementation processing a query that tests for equivalence of literals with non-recognized datatypes
(and non-identical lexical form and datatype IRI) returns an error, indicating that it
is unable to determine whether or not the values of the compared literals are equivalent. For example, an
unextended implementation will produce an error when testing <span class="queryExcerpt"><code>"iiii"^^my:romanNumeral =
"iv"^^my:romanNumeral</code></span>.
</p>
</section>

Expand Down Expand Up @@ -12743,6 +12753,9 @@ <h2>Changes between SPARQL 1.1 Query Language and SPARQL 1.2 Query Language</h2>
<li>Forbid duplicated variables in `VALUES`.</li>
<li>Add in-between term type ORDER BY support for triple terms in <a href="#modOrderBy" class="sectionRef"></a>.</li>
<li>Fixes the previously informal definition of `EXISTS` by adding a formal definition in <a href="#func-filter-exists" class="sectionRef"></a>, which includes extending the <a href="#defn_eval" class="evalFct">eval</a> function with a solution mapping <var>μ<sub>ctx</sub></var> as third argument.</li>
<li>Rename function `RDFterm-equal` as <a href="#func-sameValue"></a> and
expand the definition to cover literal arguments of differing datatypes where the
values are known to be equal or to be not equal.</li>
</ul>
</li>
<li>
Expand Down Expand Up @@ -12794,7 +12807,8 @@ <h2>Changes between SPARQL 1.1 Query Language and SPARQL 1.2 Query Language</h2>
<li><a href="https://www.w3.org/2013/sparql-errata#editorial-query-2">editorial-query-2</a>: Missing space in <a href="#defn_algJoin">Join definition</a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#editorial-query-3">editorial-query-3</a>: Incorrect link for DELETE DATA in <a href="#grammarBNodes" class="sectionRef"></a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#clarification-query-1">clarification-query-1</a>: Fix explanation of IN and NOT IN in <a href="#func-in" class="sectionRef"></a> and <a href="#func-not-in" class="sectionRef"></a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#clarification-query-2">clarification-query-2</a>: Remove unneeded reference to the semantics above in <a href="#operatorExtensibility" class="sectionRef"></a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#clarification-query-2">clarification-query-2</a>: Remove unneeded reference to the semantics above in <a href="#operatorExtensibility"
class="sectionRef"></a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#clarification-query-3">clarification-query-3</a>: Rephrase equality definition in <a href="#func-sameValue" class="sectionRef"></a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#errata-query-1">errata-query-1</a>: Let V be an empty set instead of empty multiset in <a href="#defn_evalALP">Function ALP definition</a></li>
<li><a href="https://www.w3.org/2013/sparql-errata#errata-query-2">errata-query-2</a>: Fix grammar of PropertyListPathNotEmpty in <a href="#grammar" class="sectionRef"></a></li>
Expand Down
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