Definitions for Values Insertion

[afs]

A replacement for substitute.

The context is taken from SEP-0007.

Currently, all new material is in a single section.

I am submitting this PR to put the content under the WG agreement for IP and Licensing.

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[pfps]

In my view "values insertion" is the correct phrase to use.

[pfps]

I note that this PR is for deep values insertion where values are insterted into subqueries.

[afs]

I note that this PR is for deep values insertion where values are insterted into subqueries.

Only variables are "in-scope" are affected.
The renaming apart means that variables hidden by scope in subqueries are not correlated. This is a point where correlation and the requirements of parameterisation might differ.

This query has a sub-query that exposes ?o

SELECT * {
    ?s :p ?o .
    FILTER EXISTS{ SELECT ?o { :s :q ?o }}

whereas the inner ?o in

SELECT * {
    ?s :p ?o .
    FILTER EXISTS{ SELECT ?s { ?s :q :?o }}

is not correlated.

As algebra expressions:

SELECT * {
    ?s :p ?o .
    FILTER EXISTS { SELECT * { ?s :q ?z} }

SELECT * {
    ?s :p ?o .
    FILTER EXISTS { ?s :q :?z }

are the same.