How do I call a formula on a specific graph?

[tpluscode]

I wasn't sure how to phrase it but an example speaks louder than 1000 words

@prefix log: <http://www.w3.org/2000/10/swap/log#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix ex: <http://example.com/> .

[] ex:formula { 
  { ex:foo rdfs:label "bar" } log:becomes { ex:foo rdfs:label "baz" }
} .

#[] ex:initialData {
  ex:foo rdfs:label "bar" .
#} .

{
  [] ex:formula ?formula .
  ?formula!log:call .
} => true .

The above works. If I have asserted triple, I can use the formula with log:becomes to modify it.

If I uncomment the two lines, the triples is asserted in another graph, inaccessible to my formula. Without modifying the formula, how can I use log:call or similar to evaluate it over the graph which is object of ex:initialData?

[josd]

If I uncomment the two lines, the triples is asserted in another graph

No, it is not asserted (just mentioned in a graph term) and log:becomes only works for asserted triples.

[tpluscode]

Gotcha. Can that graph be modified?

[tpluscode]

Or, to reframe it a little, could I take that graph and write a new graph which mentions a new graph?

[josd]

The only way I see is

@prefix log: <http://www.w3.org/2000/10/swap/log#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix ex: <http://example.com/> .

[] ex:formula { 
  { ?S ?P { ex:foo rdfs:label "bar" } } log:becomes { ?S ?P { ex:foo rdfs:label "baz" } }
} .

[] ex:initialData {
  ex:foo rdfs:label "bar" .
} .

{
  [] ex:formula ?formula .
  ?formula!log:call .
} => true .

[tpluscode]

I think I can work with this, thanks