--- pretty_name: Sphragis language: - grc license: other task_categories: - text-classification tags: - authorship-attribution - ancient-greek - conllu - dependency-parsing configs: - config_name: sentence_1 data_files: - split: train path: data/sentence_1/train-* - split: validation path: data/sentence_1/validation-* - split: test path: data/sentence_1/test-* - config_name: sentence_10 data_files: - split: train path: data/sentence_10/train-* - split: validation path: data/sentence_10/validation-* - split: test path: data/sentence_10/test-* - config_name: sentence_50 data_files: - split: train path: data/sentence_50/train-* - split: validation path: data/sentence_50/validation-* - split: test path: data/sentence_50/test-* - config_name: sentence_100 data_files: - split: train path: data/sentence_100/train-* - split: validation path: data/sentence_100/validation-* - split: test path: data/sentence_100/test-* --- # Sphragis ![sphragis](./sphregis_bnf_sg388_f46r.jpeg) `Sphragis` (σφραγίς, "sigil") is a benchmark for Ancient Greek (`grc`) prose and verse authorship attribution (AA). Its input is the complete curated union of the human-annotated [CoNLL-U](https://universaldependencies.org/format.html) trees in the supported treebank projects, including lemma, part of speech, morphology, and dependency relations. It defines 1-, 10-, 50-, and 100-sentence attribution tasks. The complementary scanned-line benchmark is published separately as [`Urdatorn/sphragis-metre`](https://huggingface.co/datasets/Urdatorn/sphragis-metre). >_For the archaic Greek poets, "sphragis" (or "sphregis" in some dialects) was a term of art roughly equivalent to the modern "authorial watermark", referring to text composition that intentionally aims at making it harder for adversaries to falsely pass off the work as their own. The phenomenon of "sphragizing" is one of the earliest chapters in the history of AA. (See *Theognidea*, 19-30)_ Sphragis does not require a sentence to occur in any second annotation stream. Prose and verse enter on the same basis: a retained sentence from any supported treebank is eligible. Exact duplicates are consolidated with all treebank provenance preserved. ## Tasks There are four task sizes. Prose and verse sentences share one closed-set authorship problem; the `genre` column preserves their source representation. ## Configurations | Configuration | Authors | Row unit | Train rows | Validation rows | Test rows | |---|---:|---|---:|---:|---:| | `sentence_1` | 17 | sentence | 43,300 | 4,800 | 4,800 | | `sentence_10` | 17 | 10-sentence chunk | 4,330 | 480 | 480 | | `sentence_50` | 17 | 50-sentence chunk | 866 | 96 | 96 | | `sentence_100` | 17 | 100-sentence chunk | 433 | 48 | 48 | The suffix gives the chunk size in every split. `_100` defines one shared source corpus for all four tasks: an author is retained only when that author independently has at least 100 source rows in **both** validation and test, and every split is reduced to a multiple of 100 source rows per author. `_1` publishes the shared rows atomically, while `_10`, `_50`, and `_100` regroup those exact same train, validation, and test rows into fixed benchmark chunks. Thus author inventory and total source text are identical across task sizes. Source-row selection uses seed `776`. For each retained author and split, the unavoidable `n mod 100` source rows are selected for exclusion once by a stable hash. The shared retained rows are put into their best available textual order within each work for each chunking task. Complete single-work chunks are emitted first; only residual work tails are combined, and such rows are marked by `chunk_is_mixed_work`. Chunk IDs, boundaries and exclusions are therefore reproducible. The complete manifest is in `metadata/dataset_variants.json`. Every row retains its treebank genre and provenance. ## Sentences per author label These are the exact retained atomic sentences in `sentence_1`. The same sentences are represented in the 10-, 50-, and 100-sentence configurations. | Author label | Train | Validation | Test | Total | |---|---:|---:|---:|---:| | Aeschylus | 2,600 | 300 | 300 | 3,200 (6.0%) | | Aristophanes | 1,400 | 100 | 100 | 1,600 (3.0%) | | Athenaeus | 1,900 | 200 | 200 | 2,300 (4.3%) | | Demosthenes | 2,400 | 300 | 300 | 3,000 (5.7%) | | Diodorus Siculus | 1,000 | 100 | 100 | 1,200 (2.3%) | | Dionysius of Halicarnassus | 800 | 100 | 100 | 1,000 (1.9%) | | Herodotus | 5,900 | 700 | 700 | 7,300 (13.8%) | | Homeric-Iliad | 6,200 | 700 | 700 | 7,600 (14.4%) | | Homeric-Odyssey | 4,800 | 600 | 600 | 6,000 (11.3%) | | Josephus | 800 | 100 | 100 | 1,000 (1.9%) | | Plato | 900 | 100 | 100 | 1,100 (2.1%) | | Plutarch | 1,300 | 100 | 100 | 1,500 (2.8%) | | Polybius | 3,000 | 300 | 300 | 3,600 (6.8%) | | Procopius | 900 | 100 | 100 | 1,100 (2.1%) | | Sophocles | 3,100 | 300 | 300 | 3,700 (7.0%) | | Thucydides | 900 | 100 | 100 | 1,100 (2.1%) | | Xenophon | 5,400 | 600 | 600 | 6,600 (12.5%) | | **All labels** | **43,300** | **4,800** | **4,800** | **52,900 (100.0%)** | ```python from datasets import load_dataset sentences = load_dataset("Urdatorn/sphragis", "sentence_10") ``` ## Splits Splits use random seed `776` and begin with independent stratification within each author/work group: approximately 80% train, 10% validation and 10% test by row. Groups with 3–9 rows receive one validation and one test row; groups with fewer than three stay in training. The 100-row eligibility and remainder bottleneck is then applied to all four task sizes. The train, validation, and test source sets are all exact multiples of 100 per author. This makes the published source-row ratio slightly different from the initial 80/10/10 split. A stricter work-held-out evaluation can be added as a later track. ## Principal columns All configurations contain: - `id`, `author`, `work`, `work_id`, `genre`, `text`; - `conllu`, `cts_urn`, `passage`, `treebank_source`; - `source_records`: JSON containing every contributing upstream record, revision, URL, license, annotation provenance and syntax scheme; - `licenses`, `dedup_key`, and `split`. `text` is always a JSON list of strings. Atomic `_1` rows contain one string; every split of `_10`, `_50`, and `_100` contains exactly 10, 50, or 100 separate sentence strings. No whitespace separator is used to encode unit boundaries. `conllu` is likewise always a JSON list of strings with the same number of units as `text`. The `_10`, `_50`, and `_100` configurations additionally contain `chunk_size`, `chunk_target_size`, ordered `constituent_ids`, JSON `constituent_provenance`, `chunk_work_ids`, `chunk_works`, and `chunk_is_mixed_work`. Every row has `chunk_size` equal to the configuration suffix. Aggregated `text` and `conllu` follow constituent order, while constituent provenance retains the original passage-level locations. All sentence rows share one schema. There are no metrical, scanned-line, or external-alignment columns. `genre` has exactly two values: `prose` and `verse`. ## Dependency representation Existing UD data is retained verbatim. Native AGDT/Arethusa trees are serialized as CoNLL-U while preserving heads. Their dependency relations are conservatively mapped to the Universal Dependencies v2 inventory; opaque source-specific categories fall back to `dep`. The lossless original `NativeRel` and `NativeHead` values remain in MISC for audit and future mapping improvements. Repairs required after removing artificial ellipsis nodes—or to break an upstream beta self-loop/cycle—are explicitly marked `HeadRepair=Yes`. XPOS is normalized across every source to the nine-position Ancient Greek AGDT/Perseus tag convention. Existing valid positional tags are retained; incompatible source-specific tags are reconstructed from UPOS and FEATS, with unavailable distinctions represented by `-`. UPOS and FEATS remain the canonical UD fields. Every distinct published `conllu` document is loaded during testing with the [official CoNLL 2018 shared-task `load_conllu` parser](https://github.com/CoNLL-UD-2018/UDPipe-Future/blob/master/conll18_ud_eval.py). This checks sentence termination, ten-column structure, token IDs, heads, roots and dependency cycles across all configurations. To prevent authorship-label leakage, model-facing `conllu` values retain only the non-identifying `# text = ...` comment. Comments carrying `sent_id`, `source`, `cts`, `passage`, or `newdoc id` are removed. The same information remains available for audit in the dataset's dedicated provenance columns. Token-level MISC identifiers (`Cite`, `Ref`, and `LId`) are also removed; only `NativeRel`, `NativeHead`, `HeadRepair`, and `SpaceAfter` are retained there. ## Deduplication Raw treebank input comprised 110,849 prose and verse sentences. Authorship curation retained 92,141 source sentences before deduplication. Exact normalization-based deduplication then removed 23,282 repeated rows, and 1,291 rows in 253 exact-text groups were omitted because their retained author labels conflict, leaving 67,568 eligible sentences before the shared 100-row task bottleneck. Normalization lowercases, maps final sigma, removes diacritics and retains letters only. The chosen parse follows a deterministic source priority, while all exact-source provenance is merged into `source_records`. This is aggressive exact deduplication, not passage-level fuzzy deduplication. Segmentation or edition differences can therefore leave near duplicates for future review. ## Sources and licensing The corpus draws on [AGDT 2.1](https://github.com/PerseusDL/treebank_data), [UD Perseus](https://github.com/UniversalDependencies/UD_Ancient_Greek-Perseus), [UD PROIEL](https://github.com/UniversalDependencies/UD_Ancient_Greek-PROIEL), [UD PTNK](https://github.com/UniversalDependencies/UD_Ancient_Greek-PTNK), [Gorman's Greek Dependency Trees](https://github.com/vgorman1/Greek-Dependency-Trees), [Pedalion](https://github.com/perseids-publications/pedalion-trees), and [Harrington Trees](https://github.com/perseids-publications/harrington-trees). This is a mixed-license dataset, including NonCommercial and ShareAlike data. Consult [LICENSES.md](LICENSES.md) and the licenses recorded on every row. Source commits for this release are frozen in [`metadata/source_revisions.json`](metadata/source_revisions.json). ## Conservative authorship policy The benchmark favors reliable training labels over coverage. It excludes anonymous and unknown authors, `Pseudo-*` and traditional attributions, fragment-labelled works, corporate or mediated authorship, and works or passages whose attribution is substantially disputed. This includes disputed material transmitted inside the Demosthenic, Antiphontic, Lysian, Platonic, Aeschylean, Isocratean and Xenophontic corpora, as well as the pseudo-Hesiodic *Shield of Heracles*. The core *Theogony* and *Works and Days* are retained under `Hesiod`. Romans is retained under `Paul`, while disputed and anonymous New Testament works are excluded. The *Iliad* and *Odyssey* are retained as distinct conventional corpora under the author labels `Homeric-Iliad` and `Homeric-Odyssey`; the labels do not claim a shared biographical author. Every work labelled `Fragments` is excluded. Machine-readable reasons and pre-deduplication counts are recorded in [`metadata/build_report.json`](metadata/build_report.json).