renames variables to avoid confusion that led to errata-query-11; as motivated in #94

Author: hartig

spec/index.html

@@ -8769,9 +8769,9 @@ <h5>Grouping and Aggregation</h5>
 Let E := [], a list of pairs of the form (variable, expression)
 
 If Q contains GROUP BY exprlist
-   Let G := Group(exprlist, ToList(P))
+   Let Grp := Group(exprlist, ToList(P))
 Else If Q contains an aggregate in SELECT, HAVING, ORDER BY
-   Let G := Group((1), ToList(P))
+   Let Grp := Group((1), ToList(P))
 Else
    skip the rest of the aggregate step
    End
@@ -8784,14 +8784,14 @@ <h5>Grouping and Aggregation</h5>
       End
   For each aggregate R(args ; scalarvals) now in X
       # note scalarvals may be omitted, then it's equivalent to the empty set
-      A<span><sub>i</sub></span> := Aggregation(args, R, scalarvals, G)
+      A<span><sub>i</sub></span> := Aggregation(args, R, scalarvals, Grp)
       Replace R(...) with agg<span><sub>i</sub></span> in Q
       i := i + 1
       End
   End
 
 For each variable V appearing outside of an aggregate
-   A<span><sub>i</sub></span> := Aggregation(V, Sample, {}, G)
+   A<span><sub>i</sub></span> := Aggregation(V, Sample, {}, Grp)
    E := E append (V, agg<span><sub>i</sub></span>)
    i := i + 1
    End
@@ -9763,8 +9763,8 @@ <h3>Evaluation Semantics</h3>
             <div id="defn_evalAggregation">
               <b>Definition: Evaluation of Aggregation</b>
             </div>
-            <p>eval(D(G), Aggregation(exprlist, func, scalarvals, P)) = Aggregation(exprlist, func,
-              scalarvals, eval(D(G), P))</p>
+            <p>eval(D(G), Aggregation(exprlist, func, scalarvals, Grp)) = Aggregation(exprlist, func,
+              scalarvals, eval(D(G), Grp))</p>
           </div>
           <div class="defn">
             <div id="defn_evalAggregateJoin">