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+ ---
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+ license: apache-2.0
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+ language:
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+ - af
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+ - ar
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+ - bg
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+ - bn
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+ - de
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+ - el
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+ - en
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+ - es
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+ - et
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+ - eu
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+ - fa
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+ - fi
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+ - fr
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+ - he
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+ - hi
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+ - hu
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+ - id
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+ - it
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+ - ja
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+ - jv
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+ - ka
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+ - kk
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+ - ko
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+ - ml
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+ - mr
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+ - ms
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+ - my
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+ - nl
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+ - pt
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+ - ru
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+ - sw
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+ - ta
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+ - te
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+ - th
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+ - tl
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+ - tr
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+ - ur
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+ - vi
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+ - yo
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+ - zh
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+ ---
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+
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+
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+ # Model Card for EntityCS-39-PEP_MS_MLM-xlmr-base
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+
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+ This model has been trained on the EntityCS corpus, an English corpus from Wikipedia with replaced entities in different languages.
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+ The corpus can be found in [https://huggingface.co/huawei-noah/entity_cs](https://huggingface.co/huawei-noah/entity_cs), check the link for more details.
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+
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+ Firstly, we employ the conventional 80-10-10 MLM objective, where 15% of sentence subwords are considered as masking candidates. From those, we replace subwords
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+ with [MASK] 80% of the time, with Random subwords (from the entire vocabulary) 10% of the time, and leave the remaining 10% unchanged (Same).
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+
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+ To integrate entity-level cross-lingual knowledge into the model, we propose Entity Prediction objectives, where we only mask subwords belonging
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+ to an entity. By predicting the masked entities in ENTITYCS sentences, we expect the model to capture the semantics of the same entity in different
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+ languages.
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+ Two different masking strategies are proposed for predicting entities: Whole Entity Prediction (`WEP`) and Partial Entity Prediction (`PEP`).
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+
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+ In WEP, motivated by [Sun et al. (2019)](https://arxiv.org/abs/1904.09223) where whole word masking is also adopted, we consider all the words (and consequently subwords) inside
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+ an entity as masking candidates. Then, 80% of the time we mask every subword inside an entity, and
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+ 20% of the time we keep the subwords intact. Note that, as our goal is to predict the entire masked
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+ entity, we do not allow replacing with Random subwords, since it can introduce noise and result
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+ in the model predicting incorrect entities. After entities are masked, we remove the entity indicators
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+ `<e>`, `</e>` from the sentences before feeding them to the model.
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+
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+ For PEP, we also consider all entities as masking candidates. In contrast to WEP, we do not force
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+ subwords belonging to one entity to be either all masked or all unmasked. Instead, each individual
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+ entity subword is masked 80% of the time. For the remaining 20% of the masking candidates, we experiment with three different replacements. First,
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+ PEP<sub>MRS</sub>, corresponds to the conventional 80-10-10 masking strategy, where 10% of the remaining
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+ subwords are replaced with Random subwords and the other 10% are kept unchanged. In the second
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+ setting, PEP<sub>MS</sub>, we remove the 10% Random subwords substitution, i.e. we predict the 80% masked
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+ subwords and 10% Same subwords from the masking candidates. In the third setting, PEP<sub>M</sub>, we
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+ further remove the 10% Same subwords prediction, essentially predicting only the masked subwords.
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+
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+ Prior work has proven it is effective to combine
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+ Entity Prediction with MLM for cross-lingual transfer ([Jiang et al., 2020](https://aclanthology.org/2020.emnlp-main.479/)), therefore we investigate the
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+ combination of the Entity Prediction objectives together with MLM on non-entity subwords. Specifically, when combined with MLM, we lower the
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+ entity masking probability (p) to 50% to roughly keep the same overall masking percentage.
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+ This results into the following objectives: WEP + MLM, PEP<sub>MRS</sub> + MLM, PEP<sub>MS</sub> + MLM, PEP<sub>M</sub> + MLM
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+
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+ This model was trained with the **PEP<sub>MS</sub> + MLM** objective on the EntityCS corpus with 39 languages.
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+
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+
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+ ## Model Details
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+
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+ ### Training Details
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+
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+ We start from the [XLM-R-base](https://huggingface.co/xlm-roberta-base) model and train for 1 epoch on 8 Nvidia V100 32GB GPUs.
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+ We set batch size to 16 and gradient accumulation steps to 2, resulting in an effective batch size of 256.
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+ For speedup we use fp16 mixed precision.
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+ We use the sampling strategy proposed by [Conneau and Lample (2019)](https://proceedings.neurips.cc/paper/2019/file/c04c19c2c2474dbf5f7ac4372c5b9af1-Paper.pdf), where high resource languages are down-sampled and low
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+ resource languages get sampled more frequently.
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+ We only train the embedding and the last two layers of the model.
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+ We randomly choose 100 sentences from each language to serve as a validation set, on which we measure the perplexity every 10K training steps.
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+
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+ **This checkpoint corresponds to the one with the lower perplexity on the validation set.**
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+
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+
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+ ## Usage
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+
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+ The current model can be used for further fine-tuning on downstream tasks.
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+ In the paper, we focused on entity-related tasks, such as NER, Word Sense Disambiguation and Slot Filling.
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+
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+ Alternatively, it can be used directly (no fine-tuning) for probing tasks, i.e. predict missing words, such as [X-FACTR](https://aclanthology.org/2020.emnlp-main.479/).
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+
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+ ## How to Get Started with the Model
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+
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+ Use the code below to get started with the model: https://github.com/huawei-noah/noah-research/tree/master/NLP/EntityCS
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+
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+ ## Citation
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+
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+ **BibTeX:**
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+
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+ ```html
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+ @inproceedings{whitehouse-etal-2022-entitycs,
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+ title = "{E}ntity{CS}: Improving Zero-Shot Cross-lingual Transfer with Entity-Centric Code Switching",
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+ author = "Whitehouse, Chenxi and
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+ Christopoulou, Fenia and
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+ Iacobacci, Ignacio",
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+ booktitle = "Findings of the Association for Computational Linguistics: EMNLP 2022",
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+ month = dec,
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+ year = "2022",
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+ address = "Abu Dhabi, United Arab Emirates",
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+ publisher = "Association for Computational Linguistics",
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+ url = "https://aclanthology.org/2022.findings-emnlp.499",
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+ pages = "6698--6714"
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+ }
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+ ```
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+
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+ ## Model Card Contact
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+
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+ [Fenia Christopoulou](mailto:efstathia.christopoulou@huawei.com)
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+