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Converter.to_collection walked an rdf:List chain checking only that each cell carries one rdf:first/rdf:rest pair and that the chain is acyclic. It did not check how many statements point into the chain. The @list form inlines the whole chain at a single reference and writes its cells nowhere else, so when a cell is referenced from more than one place each referring list rendered the shared cells again. The round trip then gained triples: _:tail rdf:first "b" ; rdf:rest rdf:nil . _:head rdf:first "a" ; rdf:rest _:tail . ex:s1 ex:p _:head . ex:s2 ex:p _:tail . # second reference into the chain serialized as two independent @list values, one per referring subject, so the tail was emitted twice: 6 triples in, 8 out, not isomorphic. This is the same defect class as RDFLib#3504, which fixed TurtleSerializer and LongTurtleSerializer by counting statements that point into the chain. The JSON-LD converter has its own chain walk and was not covered by that fix, so it gets the same check: a cell that is the object of more than one statement is not rendered as a list, and the chain is written out with explicit rdf:first/rdf:rest instead. An empty chain still renders as "@list": [], which is rdf:nil rather than a list structure, so nothing is lost there.
…eter The N-Triples serializer writes statements in the order the store iterates them, which follows set iteration and so varies between processes. The same graph therefore serializes to different bytes in different runs, which shows up as diff noise in version-controlled RDF. PR RDFLib#3008 solved this for longturtle with an opt-in `canon` parameter that canonicalizes the graph and sorts, fixing RDFLib#1890. This gives NTSerializer the same parameter, with the same default of False, so ordinary serialization is untouched and still streams statement by statement. `canon=True` canonicalizes with to_canonical_graph and writes the rendered rows in sorted order. Sorting the rendered rows rather than the triples keeps the order total: two distinct terms can share a str(), which would leave their relative order down to the store iteration order that this is meant to remove, whereas identical rows mean identical statements. Measured over six PYTHONHASHSEED values on a graph with a hub, a shared list tail and a deep blank-node chain: 5 distinct documents before, 1 after. NT11Serializer inherits it by subclassing.
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Integration branch — tracking only. Do not merge.
What this branch is
feat/envited-x-pipelineis upstreamRDFLib/rdflib@mainwith every contribution thisorganisation is still carrying cherry-picked on top, and nothing else. It is the branch to
check out when you need an rdflib that behaves the way our pipeline expects before
upstream has merged the relevant PRs.
It is rebased on upstream
main, never merged into. An empty cherry-pick list is the goalstate: it would mean upstream has merged everything, and the branch could be deleted.
Same convention as
ASCS-eV/linkml#14.What it currently carries
81fe1fbe342175bfcanonparameterBoth cherry-picked cleanly onto
a090f3f9with no conflicts.Each is also tracked individually as a mirrored PR: #1 and #2.
What consumes it
Nothing yet, deliberately.
asam-openx-standardspins releasedrdflib==7.6.0through
scripts/requirements.txt, anddiffable-rdfdepends on released rdflib too.That pin is the point: rdflib performs the final serialization of every generated OWL and
SHACL artifact, so a change here moves artifact bytes. Consuming this branch would mean
building from a fork, which the pipeline's reproducibility rules do not allow — the lock
records released versions precisely so a third party can obtain them.
The relationship is therefore one-directional: what lands upstream here eventually arrives
as a released rdflib that the pipeline can bump to, with regenerated artifacts in the same
change. The merged #3504 (the Turtle variant
of the RDFLib#3543 defect) is the precedent —
diffable-rdfhad to work around it until it wasreleased.