本项目由清华大学知识工程实验室维护，用于为特定领域构建科学概念/数据集。本项目设计了一个从少量文本出发，使用概念抽取，实体链接，概念扩展，交叉验证等的流程，用于获取高质量的大规模概念集。

项目的流程如下图所示，包含以下主要环节：

• ①概念抽取：从文本抽取概念

• ②④概念扩展：根据概念和外部知识(如百科)，获取更多文本语料

• ③实体链接：从文本获取已有知识库中的实体

• ⑤交叉验证：将多个环节中的概念获取方法进行交叉验证，提高获取效果

• (补充)词袋生成：通过补充概念的上下文词，提供概念的更丰富信息

• (补充)利用搜索引擎的概念判别：根据概念在搜索引擎中返回的结果，进一步判别概念是否属于目标领域

使用本项目时，可以根据实际需要，选取流程中的一个或多个工具进行概念获取。

This project is maintained by Knowledge Engineering Group of Tsinghua University(THUKEG), and is used for building a scientific concept set of a certain domain. To acquire high-quality, large-scale concept set, we design a pipeline which employs Concept Extraction, Entity Linking, Concept Extraction and Cross Valiation to get concepts from corpus.

The framework of our Concept Acquisition is shown below, including:

• ①Concept Extraction: Given texts, obtain concepts.
• ②④Concept Expansion: Given several seed concepts and external knowledge (e.g. Wikipedia or Baidubaike), get more texts.
• ③Entity Linking: Given texts, discover the entities of the existing knowledge graph(here we emply Xlore).
• ⑤Cross Validation: Multiple methods are cross validated to improve the acquisition performance.
• (Ex.)Word Bag Generation: Provide more information about concepts by generating its contextual words.
• (Ex.)Concept Classification: Further classify whether a concept belongs to the target domain using snippets from Search Engines.

Python >= 3.5, Tensorflow >= 1.10

1. run bash init.sh.
2. cd bert_start/
3. run bert_start.sh -l en|zh to start the BERT service.

• context_file: unstractured natural language context.

在数据通信中，一个物理网络节点可以是数据电路端接设备（DCE），如调制解调器、集线器、桥接器或交换机；也可以是一个数据终端设备（DTE），如数字手机，打印机或主机（例如路由器、工作站或服务器）。

• seeds: Each single line contains an unique concept.

数据
调制解调器

• extraction result: Each single line contains a json-format text with "name"(name of the concept) and "score"(confidence score of relation with seeds)

{"name": "强连通图", "score": 0.8718439936637878}

The following settings can be modified in config.py:

result_path = 'processed_data/propagation_results/result.json'
input_text = 'input_data/context/baike_context'
input_seed = 'input_data/seeds/seed_concepts'

Then excute the following command:

python concifdence_propagation.py -l zh -task extract

None: Extract Chinese concepts need setting language as 'zh', while English 'en'.

The evaluation is conducted on an running example of "Data Structure & Algorithms", we record our annotation results for evaluation, and the results are listed below. Sum of high-quality concepts: XXX.

python evaluation.py --config

You can edit the output file before next step, to get a better final result.

This process is used for searching for more related concepts or texts to expand the concept set.

• concepts: a concept list of target domain

• expanded concept list: More candidate concepts, and each concept is combined with an external web page text.

This part need developer to crawl from corresponding external knowledge. Currently we do not provide tool of this part. But a typical solution is to link the concept list at ① step to an external knowledge base, and take the entities that have relationships with these concepts as expanded concept list.

In our practice, we employ Baidubaike as the external knowledge, the example of our expanded result is in the file of XX.

From 535 concepts provided by step ①, we use the hyperlink of Baidubaike to get more concepts. Finally, we get texts for xxxx concepts in first expansion stage, and texts for xxx concepts based on 2nd-round expansion.

Entity linking is a supplement method of concept extraction, here we employ Xlink.

Xlink extract concepts that contained in Wikipedia or Baidu Baike from the given context, without knowning seeds. This toolkit ranks concept list according to the frequency of concept's occurrence in the full context.

• context_file: unstractured natural language context. (usually crawled from Baike web page of seeds)

• extraction result: Each single line contains a json-format text with "name"(name of the concept) and "freq"(frequency of that concept in the input context)

{"name": "动态规划", "freq": 68}

The following settings can be modified in config.py:

lang = "zh" 
# "zh" for extract Chinese concepts, "en" for English.
folder_path = "input_data/context"
file_name = "baike_context"
save_folder = "processed_data/xlink_results"

Then excute:

python xlink.py

python evaluation.py --config

The evaluation of Entity Linking is also conducted on "Data Structure and Algorithm". After this step, we get xxx concepts from xxx web pages.

This part includes two subsections

* 5.1 Rerank the concepts Based on Concept Extraction and Entity Linking
* 5.2 Rerank the concepts Based on Clustering

Confidence propagation method ranks concepts according to their relation with seeds, while entity linking method could check whether a word should be identified as a concept. This algorithm rerank the concept list based on the results of the two steps above.

Metric: R = log(freq) * max(score-a, 0)

• confidence propagation result: Each single line contains a json-format text with "name"(name of the concept) and "score"(confidence score of relation with seeds)

{"name": "强连通图", "score": 0.8718439936637878}

• entity link result: Each single line contains a json-format text with "name"(name of the concept) and "freq"(frequency of that concept in the input context)

{"name": "动态规划", "freq": 68}

• entity link result: Each single line contains a json-format text with "name"(name of the concept), "freq"(frequency of that concept in the input context), "score"(confidence score of relation with seeds), and "R"(value of the metric)

{"name": "数组", "freq": 572, "score": 0.8489068150520325, "R": 5.389827359494898}

The following settings can be modified in config.py:

result_path = 'processed_data/propagation_results/result.json'
save_folder = "processed_data/xlink_results"
rerank_result_path = "processed_data/rerank_results/rerank_result.json"

Then excute:

python rerank.py

Ranking results and evaluation (To be designed by Yuquan).

Clusters annotation cost less human workload than concepts annotation. This tool use k-means method with cosine distance to cluster word vectors of expanded concepts.

• seeds: Each single line contains an unique concept.
• entity link result: Each single line contains a json-format text with "name"(name of the concept), "freq"(frequency of that concept in the input context), "score"(confidence score of relation with seeds), and "R"(value of the metric)

{"name": "数组", "freq": 572, "score": 0.8489068150520325, "R": 5.389827359494898}

• clustering result: Each single line contains a json-format text with "name"(name of the concept), "freq"(frequency of that concept in the input context), "score"(confidence score of relation with seeds), "R"(value of the metric), "cluster"

{"name": "选择排序", "freq": 53, "score": 0.8094679713249207, "R": 3.2138241408307735, "cluster": 1}

Before running the program, it is required to download word vector from https://pan.baidu.com/s/1Gndr0fReIq_oJ3R34CxlPg, and unzip the file into "word_clustering\word_vectors".

num_clusters = 100 # number of clusters for all expanded concepts
num_seed_clusters = 10 # number of clusters for seeds
wordvector_path = "word_clustering/word_vectors/sgns.baidubaike.bigram-char"
cluster_concept_path = "processed_data/rerank_results/rerank_result.json"
input_seed = 'input_data/seeds/seed_concepts'

cluster_save_path = "processed_data/cluster_results/cluster_result.json"

Then excute:

python clustering.py

Ranking results and evaluation (To be designed by Yuquan).

• word bag result: "posi" for occurrence list of the concept. "pre" for concepts occur before the concept. "save" for concepts occur at the same position. "post" for concepts occur after the concept.

{"name": "选择排序", "freq": 53, "score": 0.8094679713249207, "R": 3.2138241408307735, "cluster": 1, "posi": [3, 10,...], "pre":{"列": 10, "地址": 8...}, "same":{"选择": 2}, "post":{ "查找": 4, "复杂度": 2...}}

input_text = 'input_data/context/baike_context'
cluster_save_path = "processed_data/cluster_results/cluster_result.json"
prun_length = 1000
bag_length = 20
save_word_bag = 'processed_data/word_bag_results/word_bag.json'

Then excute:

python word_bag.py

• Usage

input_text = 

Then excute:

python xxx.py

If you employ our tools or some of them for research, please cite the papers listed below.

Course Concept Extraction in Embedding-Based Graph Propagation, IJCNLP2017

@inproceedings{pan2017course,
  title={Course concept extraction in moocs via embedding-based graph propagation},
  author={Pan, Liangming and Wang, Xiaochen and Li, Chengjiang and Li, Juanzi and Tang, Jie},
  booktitle={Proceedings of the Eighth International Joint Conference on Natural Language Processing (Volume 1: Long Papers)},
  pages={875--884},
  year={2017}
}

Course Concept Expansion in MOOCs with External Knowledge and Interactive Game, ACL2019

@inproceedings{yu2019course,
  title={Course Concept Expansion in MOOCs with External Knowledge and Interactive Game},
  author={Yu, Jifan and Wang, Chenyu and Luo, Gan and Hou, Lei and Li, Juanzi and Liu, Zhiyuan and Tang, Jie},
  booktitle={Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics},
  pages={4292--4302},
  year={2019}
}

XLink: Domain Specific Entity Linking System, JIST19 (In Press)