Downstream MT evaluation of MoVoC_Tok: from-scratch MarianMT, English<->Amharic/Tigrinya, zero-shot Tigre
# MoVoC_MT: Downstream Machine Translation Evaluation of MoVoC_Tok
Real downstream validation of the MoVoC_Tok
tokenizer (built for the MoVoC project,
arXiv:2509.08812): a **from-scratch MarianMT**
model, trained bidirectionally on English↔Amharic and English↔Tigrinya, then
evaluated **zero-shot on English↔Tigre** (a third Ge'ez-script language never
seen during training) to test whether MoVoC_Tok's shared vocabulary gives any
real cross-lingual transfer. This is the kind of downstream MT validation the
MoVoC paper's own Table 3 describes, but which the MoVoC project itself never
had until now.
Model: Hailay/movoc-mt-en-am-ti on the Hugging Face Hub.
## Architecture
Matches the exact architecture of the paper's own original MarianMT run
(`Paralleldata/results/checkpoint-524316/config.json`), confirmed field-for-field:
6 encoder + 6 decoder layers, 8 attention heads, `d_model=512`, feedforward
dimension 2048, Swish activation, shared encoder/decoder embeddings, static
(sinusoidal) position embeddings. **106,104,832 parameters.**
The one deliberate difference: vocabulary. The original run used a bespoke
63,050-token vocabulary; this run uses **MoVoC_Tok's 120,000-token shared
Ge'ez-script + English SentencePiece Unigram vocabulary** instead (120,004
after adding 3 direction tags and 1 dedicated ` ` token) — still
comfortably above the ≥63,050 requirement, and the actual point of this
project: testing MoVoC_Tok downstream, not reproducing the original run
byte-for-byte.
This is a genuinely new model trained from random initialization, not a
fine-tune of any pretrained checkpoint — no pretrained MarianMT model
anywhere has a MoVoC_Tok-compatible vocabulary, and the goal is to reproduce
the paper's own from-scratch training methodology, not run a transfer-learning
experiment.
## Data
| Pair | Source | Train | Dev |
|---|---|---|---|
| English–Amharic | Raw NLLB (mined), cleaned with the same pipeline EnTiMT built for Tigrinya (NFC normalization, length/length-rat …