sclarvals empty function

Co-authored-by: Olaf Hartig <[email protected]>

Author: Tpt

spec/index.html

@@ -9555,7 +9555,7 @@ <h4>Aggregate Algebra</h4>
               <b>Definition: Aggregation</b>
             </div>
             <p>Let <i>exprlist</i> be a list of expressions or *, <i>func</i> a set function,
-              <i>scalarvals</i> a partial function (possibly empty) passed from the aggregate
+              <i>scalarvals</i> a partial function (possibly with an empty domain) passed from the aggregate
               in the query, and let { key<sub>1</sub>→Ψ<sub>1</sub>, ...,
               key<sub>m</sub>→Ψ<sub>m</sub> } be a partial function from keys to
               solution sequences as produced by the grouping step.</p>