Creating a parallel F innish- E asy F innish dataset from news articles (2023)

Abstract: Modern natural language processing tasks such as text simplification or summarization are typically formulated as monolingual machine translation tasks. This requires appropriate datasets to train, tune, and evaluate the models. This paper describes the creation of a parallel Finnish-Easy Finnish dataset from the Yle News archives. The dataset contains 1919 manually verified pairs of articles, each containing an article in Easy Finnish (selkosuomi) and a corresponding article from Standard Finnish news. Standard Finnish texts total 687555 words, and Easy Finnish texts have 106733 words. This new aligned resource was created automatically based on the Yle News archives from the Language Bank of Finland (Kielipankki) and manually checked by a human expert. The dataset is available for download from Kielipankki. This resource will allow for more effective Easy Language research and for creating applications for automatic simplification and/or summarization of Finnish texts.

## introduction easy and plain languages can be considered language varieties of different national languages with reduced linguistic complexity, which aim to improve the readability and comprehensibility of texts @xcite . however, "easy language" is not exactly a uniform concept, but more of an umbrella term @xcite . easy language media in the nordic countries have a long history, with the first documented signs of explicit usage of easy language in sweden dating back to the 1960s (ibid.). in finland, the first books and magazines in easy finnish were published in the early 1980s @xcite . right now, easy language is well-established in finland in practice, and the general attitude towards it is mainly positive (ibid.). archives of selkosuomi [easy finnish] texts are available in the language bank of finland (kielipankki 1 ). however, despite the availability of these resources, there seemingly has been no effort to create a sizeable aligned parallel corpus. our research aims to fill this gap. our corpus is based on the yle news archives available on kielipankki (yle finnish news archive 2019-2020 2 and yle news archive easyto-read finnish 2019-2020 3 ). yle is a finnish public service media company. it provides content for different audiences, including special target groups such as easy finnish language users. yle uutiset selkosuomeksi [yle news in easy finnish] provides short (about 5 minutes) daily radio and tv broadcasts. the radio broadcasts are also published on yle's website in text form. in this paper, our focus is on the news in text format. the reason for creating this corpus is twofold. first, we wanted to provide a resource for studying the simplification strategies used by simple language content providers. this task requires parallel data in which standard finnish texts are aligned with their simplified versions. second, we wanted to start working towards creating automatic text simplification tools for finnish. nowadays, automatic text simplification is typically seen as a monolingual machine translation (mt) problem @xcite , and mt models require parallel text data to train on. in this stage of our research, we have developed and applied the methodology for text alignment and manually assessed the alignments. the current dataset is available online and can be used for training models in low-resource settings. the standard finnish articles have 687555 words in total, and the easy finnish articles amount to 106733 words. ## related work parallel datasets for monolingual machine translation are often created based on news. for example, the cnn / dailymail dataset @xcite of unique news articles written by journalists at cnn and the daily mail is used for abstractive and extractive summarization, and the paraphraserplus corpus @xcite , which contains pairs of similar news headlines, is used for paraphrase generation. news-based corpora are also used for simplification, such as the newsela corpus, which consists of news articles simplified manually by professional editors @xcite . to align easy finnish articles with standard finnish equivalents, we used sentence embeddings. multilingual sentence embeddings are often applied in paraphrase identification: for example, @xcite showed that publicly available, pretrained models already achieve solid performance on this task. @xcite also prove the advantages of using the fine-tuned sentence-bert language model for classifying paraphrased sentences over other modern models. current research on easy finnish covers many different resources and methods. one of the most recent papers containing corpus-based research focuses on the meanings of the word ihminen [human] and its usage in easy finnish and standard finnish news articles @xcite . it is a good example of research that could potentially benefit from our parallel corpus. @xcite takes spoken easy finnish as a primary topic, and @xcite focuses on the cognitive accessibility assessment of different service websites. according to the interviews conducted by kulkki-nieminen (2010), the main three target groups for news in easy finnish are immigrants, older adults, and people with intellectual disabilities. when yle uutiset selkosuomeksi started broadcasting, however, it was primarily aimed at heritage finnish speakers who had learned finnish at home but were no longer in the finnish language environment (p. seppä, personal communication, march 3, 2023). @xcite conducted the interviews about the main topic of their research, namely the linguistic analysis of the language feature specific to easy finnish texts. ## evaluation we ended up with 1919 pairs of articles with high (≥ 0.6) similarity scores. an expert was asked to evaluate each pair and give it one of three scores: "positive" -if the articles are definitely about the same topic, "negative" -if the articles definitely talk about different topics, or "neutral" -if it cannot be definitively said whether or not the articles talk about the same topic. the expert also gave comments on most of the negative cases. as seen in figure 2 , the percentage of negative labels grows with the decline of the similarity score. therefore, we conclude that the cosine similarity indeed represents the semantic similarity of texts as seen by a human expert, and since the percentage of positive texts with labels between 0.6 and 0.7 is approx. 52%, there is no need to decrease the lower similarity threshold. there are 1257 "positive", 470 "negative", and 192 "neutral" article pairs in the dataset. therefore, 65.5% of the data is "positive", 24.5% is "negative", and 10% is "neutral". these assessments can be used for classifying article pairs automatically, allowing for the creation of larger parallel datasets from the remaining yle news archives. the most common reasons for giving a pair of articles a "negative" or "neutral" score were as such: it should be noted that some topics like brexit, coronavirus, or weather forecasts were challenging to evaluate, especially when no particular time markers were mentioned. due to the number of news on the same topic being too high, it was sometimes difficult to establish if two similar articles were definitely talking about the same event. there were also cases when the easy finnish article covered a topic relevant to the entire country of finland, but the standard finnish article was limited only to one particular region (e.g., lapland). during the assessment, the expert compared the simplification strategies they saw in the easy finnish articles to the easy finnish indicator/selkomittari 2.0. foot_4 selkomittari is a document that outlines the criteria for assessing how simple the text is. however, we did not use it to determine the quality of simplification but to see which strategies easy language content authors use in their work. according to the expert, the following characteristics are present in most of the simplified articles: it should be noted that in some cases, the vocabulary of easy finnish articles was not easy. for example, the expert has encountered the word amurinleopardikissapariskunta (the pair of amur leopards), which was not used even in the original news article. other cases of not-so-easy linguistic constructions found by the expert include complex sentence structures (in one case, a long sentence with four subordinate clauses) and colloquialisms without any additional comments on their meaning. there were also easy finnish articles that just summarized the original ones with no sentence-level simplification. obviously, not everything needs to be simplified. sometimes, the authors of easy finnish texts will use complex words or constructions if they consider it necessary based on their expertise. the only reason we need to point out that sometimes the easy finnish articles might have "difficult" sentences is for other researchers to be aware of such cases. for example, suppose someone wants to make a sentence-aligned dataset based on standard and easy finnish news to train an automatic text simplification model on. in that case, filtering out the not-so-easy easy finnish sentences may be beneficial before training. ## conclusions we have described the creation of a parallel finnish-easy finnish dataset based on news articles. with the help of a human assessor, we evaluated the automatically aligned pairs of articles, which helped us to determine the optimal similarity threshold and identify various cases of incorrect or ambiguous alignments. we also describe some of the simplification strategies used by authors during the creation of easy finnish articles. this resource is now available for download on kielipankki under the clarin aca -nc license: http://urn.fi/urn:nbn:fi : lb-2022111625. the dataset can be used to study the linguistic properties of simplified finnish and for various natural language processing applications. for example, it can be used for lowresource simplification or summarization. an example dataset entry can be seen in some steps can be taken to improve our data collection procedures further. for example, a valuable contribution would be to find a way to match easy finnish articles to swedish sources or standard finnish ones from different dates without it being too computationally expensive. currently, we are working on extending the dataset and adding sentence-to-sentence alignments to create a more extensive dataset suitable for text simplification.