File size: 4,802 Bytes
94edbd3
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
---

language: el
pipeline_tag: zero-shot-classification
tags:
- xlm-roberta-base
datasets:
- multi_nli
- snli
- allnli_greek
metrics:
- accuracy
license: apache-2.0
widget:
- text: "Το Facebook κυκλοφόρησε τα πρώτα «έξυπνα» γυαλιά επαυξημένης πραγματικότητας"
  candidate_labels: "πολιτική, τεχνολογία, αθλητισμός"
---


# Cross-Encoder for Greek Natural Language Inference (Textual Entailment) & Zero-Shot Classification 
This model was trained using [SentenceTransformers](https://sbert.net) [Cross-Encoder](https://www.sbert.net/examples/applications/cross-encoder/README.html) class.
#### By the
## Training Data
The model was trained on the the Greek version of the combined AllNLI dataset([SNLI](https://nlp.stanford.edu/projects/snli/) and [MultiNLI](https://cims.nyu.edu/~sbowman/multinli/)) which was created using EN2EL NMT model available [here](https://huggingface.co/lighteternal/SSE-TUC-mt-en-el-cased).

The model can be used in two ways:
* NLI/Textual Entailment: For a given sentence pair, it will output three scores corresponding to the labels: contradiction, entailment, neutral.
* Zero-shot classification through the Huggingface pipeline: Given a sentence and a set of labels/topics, it will output the likelihood of the sentence belonging to each of the topic. Under the hood, the logit for entailment between the sentence and each label is taken as the logit for the candidate label being valid.

## Performance

Evaluation on classification accuracy (entailment, contradiction, neutral) on mixed (Greek+English) AllNLI-dev set:
| Metric | Value |
| --- | --- |
| Accuracy | 0.8409 |



## To use the model for NLI/Textual Entailment

#### Usage with sentence_transformers



Pre-trained models can be used like this:

```python

from sentence_transformers import CrossEncoder
model = CrossEncoder('MODEL_NAME')

scores = model.predict([('Δύο άνθρωποι συναντιούνται στο δρόμο', 'Ο δρόμος έχει κόσμο'),

                        ('Ένα μαύρο αυτοκίνητο ξεκινάει στη μέση του πλήθους.', 'Ένας άντρας οδηγάει σε ένα μοναχικό δρόμο'), 

                        ('Δυο γυναίκες μιλάνε στο κινητό', 'Το τραπέζι ήταν πράσινο')])





#Convert scores to labels

label_mapping = ['contradiction', 'entailment', 'neutral']
labels = [label_mapping[score_max] for score_max in scores.argmax(axis=1)]

print(scores, labels)



# Οutputs

#[[-3.1526504  2.9981945 -0.3108107]

# [ 5.0549307 -2.757949  -1.6220676]

# [-0.5124733 -2.2671669  3.1630592]] ['entailment', 'contradiction', 'neutral']

 ```

 

#### Usage with Transformers AutoModel

You can use the model also directly with Transformers library (without SentenceTransformers library):

```python

from transformers import AutoTokenizer, AutoModelForSequenceClassification

import torch



model = AutoModelForSequenceClassification.from_pretrained('MODEL_NAME')

tokenizer = AutoTokenizer.from_pretrained('MODEL_NAME')



features = tokenizer(['Δύο άνθρωποι συναντιούνται στο δρόμο', 'Ο δρόμος έχει κόσμο'], 

                    ['Ένα μαύρο αυτοκίνητο ξεκινάει στη μέση του πλήθους.', 'Ένας άντρας οδηγάει σε ένα μοναχικό δρόμο.'],  

                    padding=True, truncation=True, return_tensors="pt")

model.eval()
with torch.no_grad():

    scores = model(**features).logits

    label_mapping = ['contradiction', 'entailment', 'neutral']

    labels = [label_mapping[score_max] for score_max in scores.argmax(dim=1)]

    print(labels)

```



## To use the model for Zero-Shot Classification

This model can also be used for zero-shot-classification:

```python

from transformers import pipeline



classifier = pipeline("zero-shot-classification", model='MODEL_NAME')



sent = "Το Facebook κυκλοφόρησε τα πρώτα «έξυπνα» γυαλιά επαυξημένης πραγματικότητας"

candidate_labels = ["πολιτική", "τεχνολογία", "αθλητισμός"]

res = classifier(sent, candidate_labels)

print(res)

``` 

### Acknowledgement

The research work was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the HFRI PhD Fellowship grant (Fellowship Number:50, 2nd call)



### Citation info

Citation for the Greek model TBA.

Based on the work [Sentence-BERT: Sentence Embeddings using Siamese BERT-Networks](https://arxiv.org/abs/1908.10084)

Kudos to @nreimers (Nils Reimers) for his support on Github .