license: cc-by-4.0
language:
- el
pretty_name: MORFES
size_categories:
- n<1K
annotations_creators:
- expert-generated
language_creators:
- expert-generated
source_datasets:
- original
task_categories:
- multiple-choice
- text-generation
tags:
- morphology
- inflection
- modern-greek
- greek
- linguistics
- evaluation
configs:
- config_name: default
data_files:
- split: test
path: morfes.csv
MORFES (Morphological Open-class Recognition-and-Formation Evaluation Suite; also μορφές, Greek for "forms") is a benchmark of 500 expert-verified items testing productive inflectional competence in Modern Greek.
- Task: Modern Greek inflectional morphology (recognition and production)
- Languages: Greek
- Size: 500 items
- License: CC-BY-4.0
Sophea-Genesis-1, an open Greek language model, is released alongside it.
On MORFES it is the most accurate of the open models we evaluated.
Given a lemma (dictionary form) and a grammatical specification, each item probes whether a model can recognize and produce the correct inflected form. MORFES favors lower-frequency lemmas so that a correct answer reflects the productive rule rather than a memorized form. The full construct, item selection, frequency control, and evaluation are described in the accompanying paper.
Categories
The 500 items span six categories: the three richly inflecting open classes (noun, adjective, verb), each in a single-form and a full-paradigm variant.
| Category | Items |
|---|---|
| Noun declension: single form | 50 |
| Noun declension: full paradigm | 50 |
| Adjective declension: single form | 50 |
| Adjective declension: full paradigm | 50 |
| Verb conjugation: single form | 150 |
| Verb conjugation: full paradigm | 150 |
A single-form item asks for one cell of a paradigm (for example the genitive singular of a noun); a full-paradigm item asks for a complete sub-table (for example all six persons of a verb tense). The set is verb-weighted, with 300 of the 500 items verbs: the verb is the most richly inflecting of the three, with far more distinct forms than a noun or adjective, so an equal split would under-sample the open class that inflects the most.
Data fields
One row per item, 10 columns:
| Column | Description |
|---|---|
id |
Stable item identifier, for example gr-00001. |
category |
One of the six categories above. |
question |
The item prompt, in Greek. |
A, B, C, D |
The four candidate forms. Their order is randomized per item. |
answer |
The letter (A to D) of the correct option. |
accepted_answers |
The correct surface form(s), as a JSON string: a flat list for single-form items (for example ["θέρισαν", "θερίσανε"], the aorist third-person plural of «θερίζω», "to reap"), and a list of per-cell lists for full-paradigm items. Greek often admits more than one correct form for a single specification. |
lemma |
The base (dictionary) form the item is built on. One distinct lemma per item. |
The file is a UTF-8 CSV; standard loaders read it directly:
from datasets import load_dataset
ds = load_dataset("KIEFERSA/MORFES", split="test")
Contamination control
Each item's lemma is provided so users can hold these lemmas out of a model's training data and guard against contamination. Every item is built on a distinct lemma, and the requested form is never the lemma's dictionary form, so no item can be answered by repeating a word from the prompt.
Citation
If you use MORFES, please cite:
@misc{perros2026morfes,
title = {{MORFES}: A Benchmark for Productive Inflectional Competence in Modern Greek},
author = {Perros, Ioakeim and Papadopoulou, Cleopatra and Kirouane, Ayoub and Petrocheilos, Christos},
year = {2026},
howpublished = {\url{https://huggingface.co/datasets/KIEFERSA/MORFES}},
note = {arXiv:2607.28274}
}
License
MORFES is released under the Creative Commons Attribution 4.0 International (CC-BY-4.0) license. You may share and adapt the data, including for commercial use, provided you give appropriate attribution; please attribute by citing the paper above.