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Semantic Text Similarity Dataset Hub

A typical NLP machine learning task involves classifying a sequence of tokens such as a sentence or a document, i.e. approximating a function

f_1(s) ∈ [0,1]

(where f_1 may determine a domain, sentiment, etc.). But there is a large class of problems that are often harder and involve classifying a pair of sentences:

f_2(s1, s2) ∈ [0,1]*c

(where s1, s2 are sequences of tokens and c is a rescaling factor like c=5).

Typically, the function f_2 denotes some sort of semantic similarity, that is whether (or how much) the two parameters "say the same thing". (However, the function could do something else - like classify entailment or contradiction or just topic relatedness. We may include such datasets as well.)

This repo aims to gather a variety of standard datasets and tools for training and evaluating such models in a single place, with the base belief that it should be possible to build generic models for f_2 that aren't tailored to particular tasks (and even multitask learning should be possible).

Most of the datasets are pre-existing; text similarity datasets that may be redistributed (at least for research purposes) are included. Always check the licence of a particular dataset. Some datasets may be original though, because we are working on many applied problems that pertain training such a function...

The contents of dataset-sts and baseline results are described in the paper Sentence Pair Scoring: Towards Unified Framework for Text Comprehension. Hypothesis evaluation task is described in the paper Joint Learning of Sentence Embeddings for Relevance and Entailment presented at the repl4nlp workshop at ACL2016 (poster).

Pull requests welcome that extend the datasets, or add important comments, references or attributions. Please let us know if we misread some licence terms and shouldn't be including something, we'll take that down right away!

Pull request that include simple baselines for f_2 models are also welcome. (Simple == they fit in a couple of screenfuls of code and are batch-runnable. Python is preferred, but not mandatory.)

Software Tools

To get started with simple classifiers that use task-specific code, look at the examples/ directory. To get started with task-universal deep learning models, look at the tools/, models/ and tasks/ directory.

  • pysts/ Python module contains various tools for easy loading, manipulation and evaluation of the dataset.

  • pysts/kerasts the KeraSTS allows easy prototyping of deep learning models for many of the included tasks using the Keras library.

  • examples/ contains a couple of simple, self-contained baselines on various tasks.

  • models/ directory contains various strong baseline models using the KeraSTS toolkit, including state-of-art neural networks

  • tasks/ directory contains model-independent interfaces to datasets for various tasks (from Answer Sentence Selection to Paraphrasing)

  • tools/ directory contains tools that put models and tasks together; training, evaluating, tuning and transferring models on tasks


This is for now as much a TODO list as an overview.

"Paraphrasing" Task

These datasets are about binary classification of independent sentence (or multi-sentence) pairs regarding whether they say the same thing; for example if they describe the same event (with same data), ask the same question, etc.

"Semantic Text Similarity" Task

These datasets consider the semantic similarity of independent pairs of texts (typically short sentences) and share a precise similarity metric definition of assigning a number between 0 to 5 to each pair denoting the level of similarity/entailment.

  • data/sts/semeval-sts/ SemEval STS Task - multiple years, each covers a bunch of topics that share the same precise similarity metric definition

  • data/sts/sick2014/ SemEval SICK2014 Task

  • SemEval 2014 Cross-level Semantic Similarity Task (TODO; 500 paragraph-to-sentence training items)

"Entailment" Task

These datasets classify independent pairs of "hypothesis" and "fact" sentences as entailment, contradiction or unknown.

"Answer Sentence Selection" Task

These datasets concern a "bipartite ranking" task. That is, each tuple of sentences is binary classified, but there are many different S1 sentences given the same S0 and the ultimate goal is to sort positive-labelled S1s above negative-labelled S1s for each S0.

Typically, S0 is a question and S1 are potentially-answer-bearing passages (in that case, identifying the actual answer might be an auxiliary task to consider; see anssel-yodaqa). However, other scenarios are possible, like the Ubuntu Dialogue Corpus where S1 are dialogue followups to S0.

  • data/anssel/wang/ Answer Sentence Selection - original Wang dataset

  • data/anssel/yodaqa/ Answer Sentence Selection - YodaQA-based

  • InsuranceQA Dataset (used in recent IBM papers, 25k question-answer pairs; unclear licencing)

  • data/anssel/wqmprop/ Property Path Selection (based on WebQuestions + YodaQA)

  • data/anssel/ubuntu/ The Ubuntu Dialogue Corpus contains pairs of sequences where the second sentence is a candidate for being a followup in a community techsupport chat dialog. 10M pairs make this awesome.

"Hypothesis Evidencing" Task

Similar to the "Answer Sentence Selection" task, these datasets need to consider a variety of S1 given a fixed S0 - the desired output should be however a judgement about S0 alone (typically true / false).

  • data/hypev/argus/ Argus Dataset (Yes/No Question vs. News Headline)

  • data/hypev/ai2-8grade/ AI2 8th Grade Science Questions are 641 school Science quiz questions (A/B/C/D test format), stemming from The Allen AI Science Challenge We are going to produce a dataset that merges questions and answers in a single sentence, and pairs each with potential-evidencing sentences from Wikipedia and CK12 textbooks. This will be probably the hardest dataset by far included in this repo for some time. (We may also want to include the Elementary dataset.)

  • bAbI has a variety of datasets, especially re memory networks (memory relevant to a given question), though with an extremely limited vocabulary.

  • data/hypev/mctest/ Machine Comprehension Test (MCTest) contains 300 children stories with many sentences and 4 questions each. A share-alike type licence.

  • More "Entrance Exam" tasks solving multiple-choice school tests.

Other Datasets

Some datasets are not universally available, but we may accept contributions regarding code to load them.

Non-Redistributable Datasets

Some datasets cannot be redistributed. Therefore, some scientists may not be able to agree with the licence and download them, and/or may decide not to use them for model development and research (if it is in commercial setting), but only for some final benchmarks to benefit cross-model comparisons. We discourage using these datasets.

Non-free Datasets

Some datasets are completely non-free and not available on the internet, therefore as strong believers in reproducible experiments and open science, we strongly discourage their usage.

Algorithm References

Here, we refer to some interesting models for sentence pair classification. We focus mainly on papers that consider multiple datasets or are hard to find; you can read e.g. about STS winners on the STS wiki, about anssel/wang models on the ACL wiki, about RTE models on the SNLI page.

Licence and Attribution

Always check the licences of the respective datasets you are using! Some of them are plain CC-BY, others may be heavily restricted e.g. for non-commercial use only. Default licence for anything else in this repository is ASLv2 for the code, CC-BY 4.0 for data.

Work on this project has been in part kindly sponsored by the Medialab foundation (, a Czech Technical University incubator. The rest of contributions by Petr Baudiš is licenced as open source via Ailao ( (Ailao also provides commercial consulting, customization, deployment and support services.)


Semantic Text Similarity Dataset Hub






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