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Turn the input to Group(..) and to Aggregation(..) into solution sequences #98

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Jun 29, 2023
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Turn the input to Group(..) and to Aggregation(..) into solution sequences #98

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ddf4206
initial changes to turn the input to Group(..) and to Aggregation(..)…
hartig Jun 14, 2023
c2fe1cc
extends the definition of Distinct(Ψ) to be applicable to sequences o…
hartig Jun 15, 2023
e95109b
changes the definitions of the set functions such that they are defin…
hartig Jun 15, 2023
67ac56e
Apply suggestions from code review
hartig Jun 15, 2023
ff80086
improved definition of Distinct; as per https://github.com/w3c/sparql…
hartig Jun 16, 2023
d808fb8
reverts the change to Distinct and introduces Dedup instead, as sugge…
hartig Jun 18, 2023
8e30456
Removing the <code> elements again from the algorithm.
hartig Jun 22, 2023
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39 changes: 21 additions & 18 deletions spec/index.html
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Expand Up @@ -9368,22 +9368,10 @@ <h3>SPARQL Algebra</h3>
</div>
<div class="defn">
<p><b>Definition: <span id="defn_algDistinct">Distinct</span></b></p>
<p>Let <var>Ψ</var> be a sequence of elements which may be either solution mappings or lists of RDF terms.</p>
<p>Distinct(<var>Ψ</var>) is a sequence of elements that has the following properties.</p>
<ol>
<li>Every element in <var>Ψ</var> is contained in Distinct(<var>Ψ</var>).</li>
<li>Every element in Distinct(<var>Ψ</var>) is contained in <var>Ψ</var>.</li>
<li>Distinct(<var>Ψ</var>) is free of duplicates. That is, the element at the |i|-th position in Distinct(<var>Ψ</var>) is different from the element at the |j|-th position in Distinct(<var>Ψ</var>) for every two natural numbers |i| and |j| such that |i| &ne; |j|.
</li>
<li>For every two elements <var>e<sub>1</sub></var> and <var>e<sub>2</sub></var> in Distinct(<var>Ψ</var>), the relative order of their first occurrences in <var>Ψ</var> is preserved in Distinct(<var>Ψ</var>). That is, if <var>i<sub>1</sub></var>&nbsp;&lt;&nbsp;<var>i<sub>2</sub></var>, then <var>j<sub>1</sub></var>&nbsp;&lt;&nbsp;<var>j<sub>2</sub></var>, where
<ul>
<li><var>i<sub>1</sub></var> is the smallest natural number such that <var>e<sub>1</sub></var> is at the <var>i<sub>1</sub></var>-th position in <var>Ψ</var>,</li>
<li><var>i<sub>2</sub></var> is the smallest natural number such that <var>e<sub>2</sub></var> is at the <var>i<sub>2</sub></var>-th position in <var>Ψ</var>,</li>
<li><var>j<sub>1</sub></var> is the position of <var>e<sub>1</sub></var> in Distinct(<var>Ψ</var>), and</li>
<li><var>j<sub>2</sub></var> is the position of <var>e<sub>2</sub></var> in Distinct(<var>Ψ</var>).</li>
</ul>
</li>
</ol>
<p>Let Ψ be a sequence of solution mappings. We define:</p>
<p>Distinct(Ψ) = [ μ | μ in Ψ ]</p>
<p>card[Distinct(Ψ)](μ) = 1</p>
<p>The order of Distinct(Ψ) must preserve any ordering given by OrderBy.</p>
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</div>
<div class="defn">
<p><b>Definition: <span id="defn_algReduced">Reduced</span></b></p>
Expand Down Expand Up @@ -9469,10 +9457,25 @@ <h4>Aggregate Algebra</h4>
<p>where<br>
&nbsp;&nbsp;M(Ψ) = [ ListEval(exprlist, μ) | μ in Ψ ]<br>
&nbsp;&nbsp;F(Ψ) = func(M(Ψ), scalarvals), for non-<code>DISTINCT</code><br>
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&nbsp;&nbsp;F(Ψ) = func(Distinct(M(Ψ)), scalarvals), for <code>DISTINCT</code></p>
&nbsp;&nbsp;F(Ψ) = func(Dedup(M(Ψ)), scalarvals), for <code>DISTINCT</code></p>
<p>with Dedup(M(Ψ)) being an order-preserving, duplicate-free version of the sequence M(Ψ); that is, Dedup(M(Ψ)) is a sequence of RDF terms that has the following four properties.</p>
<ol>
<li>Every unique element in M(Ψ) is contained in Dedup(M(Ψ)).</li>
<li>Every element in Dedup(M(Ψ)) is contained in M(Ψ).</li>
<li>Dedup(M(Ψ)) is free of duplicates. That is, the element at the |i|-th position in Dedup(M(Ψ)) is not the same term as the element at the |j|-th position in Dedup(M(Ψ)) for every two natural numbers |i| and |j| such that |i| &ne; |j|.</li>
<li>For any two elements <var>e<sub>1</sub></var> and <var>e<sub>2</sub></var> in Dedup(M(Ψ)), the relative order of their first occurrences in M(Ψ) is preserved in Dedup(M(Ψ)). That is, if <var>i<sub>1</sub></var>&nbsp;&lt;&nbsp;<var>i<sub>2</sub></var>, then <var>j<sub>1</sub></var>&nbsp;&lt;&nbsp;<var>j<sub>2</sub></var>, where
<ul>
<li><var>i<sub>1</sub></var> is the smallest natural number such that <var>e<sub>1</sub></var> is at the <var>i<sub>1</sub></var>-th position in M(Ψ),</li>
<li><var>i<sub>2</sub></var> is the smallest natural number such that <var>e<sub>2</sub></var> is at the <var>i<sub>2</sub></var>-th position in M(Ψ),</li>
<li><var>j<sub>1</sub></var> is the position of <var>e<sub>1</sub></var> in Dedup(M(Ψ)), and</li>
<li><var>j<sub>2</sub></var> is the position of <var>e<sub>2</sub></var> in Dedup(M(Ψ)).</li>
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</ul>
</li>
</ol>

<p><b>Special Case:</b> when <code>COUNT</code> is used with the expression
<code>*</code> the value of F will be the cardinality of the group solution sequence,
<code>card[Ψ]</code>, or <code>card[Distinct(Ψ)]</code> if the <code>DISTINCT</code>
<code>card[Ψ]</code>, or <code>card[Dedup(Ψ)]</code> if the <code>DISTINCT</code>
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keyword is present.</p>
</div>
<p><i>scalarvals</i> are used to pass values to the underlying set function, bypassing
Expand Down