prompt_front: You are given a scientific article and a question. Answer the question as concisely as you can, using a single phrase or sentence if possible. If the question cannot be answered based on the information in the article, write "unanswerable". If the question is a yes/no question, answer "yes", "no", or "unanswerable". Do not provide any explanation.

Please answer the questions based on the text provided below. by how much did their model improve?
Context 1: Introduction
Text simplification aims to reduce the lexical and structural complexity of a text, while still retaining the semantic meaning, which can help children, non-native speakers, and people with cognitive disabilities, to understand text better  One of the methods of automatic text simplification can be generally divided into three categories: lexical simplification (LS) BIBREF0 , BIBREF1 , rule-based BIBREF2 , and machine translation (MT) BIBREF3 , BIBREF4   LS is mainly used to simplify text by substituting infrequent and difficult words with frequent and easier words  However, there are several challenges for the LS approach: a great number of transformation rules are required for reasonable coverage and should be applied based on the specific context; third, the syntax and semantic meaning of the sentence is hard to retain  Rule-based approaches use hand-crafted rules for lexical and syntactic simplification, for example, substituting difficult words in a predefined vocabulary  However, such approaches need a lot of human-involvement to manually define these rules, and it is impossible to give all possible simplification rules  MT-based approach has attracted great attention in the last several years, which addresses text simplification as a monolingual machine translation problem translating from 'ordinary' and 'simplified' sentences 
In recent years, neural Machine Translation (NMT) is a newly-proposed deep learning approach and achieves very impressive results BIBREF5 , BIBREF6 , BIBREF7   Unlike the traditional phrased-based machine translation system which operates on small components separately, NMT system is being trained end-to-end, without the need to have external decoders, language models or phrase tables  Therefore, the existing architectures in NMT are used for text simplification BIBREF8 , BIBREF4   However, most recent work using NMT is limited to the training data that are scarce and expensive to build  Language models trained on simplified corpora have played a central role in statistical text simplification BIBREF9 , BIBREF10   One main reason is the amount of available simplified corpora typically far exceeds the amount of parallel data  The performance of models can be typically improved when trained on more data  Therefore, we expect simplified corpora to be especially helpful for NMT models 
In contrast to previous work, which uses the existing NMT models, we explore strategy to include simplified training corpora in the training process without changing the neural network architecture  We first propose to pair simplified training sentences with synthetic ordinary sentences during training, and treat this synthetic data as additional training data  We obtain synthetic ordinary sentences through back-translation, i e  an automatic translation of the simplified sentence into the ordinary sentence BIBREF11   Then, we mix the synthetic data into the original (simplified-ordinary) data to train NMT model  Experimental results on two publicly available datasets show that we can improve the text simplification quality of NMT models by mixing simplified sentences into the training set over NMT model only using the original training data 
Related Work
Automatic TS is a complicated natural language processing (NLP) task, which consists of lexical and syntactic simplification levels BIBREF12   It has attracted much attention recently as it could make texts more accessible to wider audiences, and used as a pre-processing step, improve performances of various NLP tasks and systems BIBREF13 , BIBREF14 , BIBREF15   Usually, hand-crafted, supervised, and unsupervised methods based on resources like English Wikipedia and Simple English Wikipedia (EW-SEW) BIBREF10 are utilized for extracting simplification rules  It is very easy to mix up the automatic TS task and the automatic summarization task BIBREF3 , BIBREF16 , BIBREF6   TS is different from text summarization as the focus of text summarization is to reduce the length and redundant content 
At the lexical level, lexical simplification systems often substitute difficult words using more common words, which only require a large corpus of regular text to obtain word embeddings to get words similar to the complex word BIBREF1 , BIBREF9   Biran et al  BIBREF0 adopted an unsupervised method for learning pairs of complex and simpler synonyms from a corpus consisting of Wikipedia and Simple Wikipedia  At the sentence level, a sentence simplification model was proposed by tree transformation based on statistical machine translation (SMT) BIBREF3   Woodsend and Lapata BIBREF17 presented a data-driven model based on a quasi-synchronous grammar, a formalism that can naturally capture structural mismatches and complex rewrite operations  Wubben et al  BIBREF18 proposed a phrase-based machine translation (PBMT) model that is trained on ordinary-simplified sentence pairs  Xu et al  BIBREF19 proposed a syntax-based machine translation model using simplification-specific objective functions and features to encourage simpler output 
Compared with SMT, neural machine translation (NMT) has shown to produce state-of-the-art results BIBREF5 , BIBREF7   The central approach of NMT is an encoder-decoder architecture implemented by recurrent neural networks, which can represent the input sequence as a vector, and then decode that vector into an output sequence  Therefore, NMT models were used for text simplification task, and achieved good results BIBREF8 , BIBREF4 , BIBREF20   The main limitation of the aforementioned NMT models for text simplification depended on the parallel ordinary-simplified sentence pairs  Because ordinary-simplified sentence pairs are expensive and time-consuming to build, the available largest data is EW-SEW that only have 296,402 sentence pairs  The dataset is insufficiency for NMT model if we want to NMT model can obtain the best parameters  Considering simplified data plays an important role in boosting fluency for phrase-based text simplification, and we investigate the use of simplified data for text simplification  We are the first to show that we can effectively adapt neural translation models for text simplifiation with simplified corpora 
Simplified Corpora
We collected a simplified dataset from Simple English Wikipedia that are freely available, which has been previously used for many text simplification methods BIBREF0 , BIBREF10 , BIBREF3   The simple English Wikipedia is pretty easy to understand than normal English Wikipedia  We downloaded all articles from Simple English Wikipedia  For these articles, we removed stubs, navigation pages and any article that consisted of a single sentence  We then split them into sentences with the Stanford CorNLP BIBREF21 , and deleted these sentences whose number of words are smaller than 10 or large than 40  After removing repeated sentences, we chose 600K sentences as the simplified data with 11 6M words, and the size of vocabulary is 82K 
Text Simplification using Neural Machine Translation
Our work is built on attention-based NMT BIBREF5 as an encoder-decoder network with recurrent neural networks (RNN), which simultaneously conducts dynamic alignment and generation of the target simplified sentence 
The encoder uses a bidirectional RNN that consists of forward and backward RNN  Given a source sentence INLINEFORM0 , the forward RNN and backward RNN calculate forward hidden states INLINEFORM1 and backward hidden states INLINEFORM2 , respectively  The annotation vector INLINEFORM3 is obtained by concatenating INLINEFORM4 and INLINEFORM5  
The decoder is a RNN that predicts a target simplificated sentence with Gated Recurrent Unit (GRU) BIBREF22   Given the previously generated target (simplified) sentence INLINEFORM0 , the probability of next target word INLINEFORM1 is DISPLAYFORM0
where INLINEFORM0 is a non-linear function, INLINEFORM1 is the embedding of INLINEFORM2 , and INLINEFORM3 is a decoding state for time step INLINEFORM4  
State INLINEFORM0 is calculated by DISPLAYFORM0
where INLINEFORM0 is the activation function GRU 
The INLINEFORM0 is the context vector computed as a weighted annotation INLINEFORM1 , computed by DISPLAYFORM0
where the weight INLINEFORM0 is computed by DISPLAYFORM0 DISPLAYFORM1
where INLINEFORM0 , INLINEFORM1 and INLINEFORM2 are weight matrices  The training objective is to maximize the likelihood of the training data  Beam search is employed for decoding 
Synthetic Simplified Sentences
We train an auxiliary system using NMT model from the simplified sentence to the ordinary sentence, which is first trained on the available parallel data  For leveraging simplified sentences to improve the quality of NMT model for text simplification, we propose to adapt the back-translation approach proposed by Sennrich et al  BIBREF11 to our scenario  More concretely, Given one sentence in simplified sentences, we use the simplified-ordinary system in translate mode with greedy decoding to translate it to the ordinary sentences, which is denoted as back-translation  This way, we obtain a synthetic parallel simplified-ordinary sentences  Both the synthetic sentences and the available parallel data are used as training data for the original NMT system 
Evaluation
We evaluate the performance of text simplification using neural machine translation on available parallel sentences and additional simplified sentences 
Dataset  We use two simplification datasets (WikiSmall and WikiLarge)  WikiSmall consists of ordinary and simplified sentences from the ordinary and simple English Wikipedias, which has been used as benchmark for evaluating text simplification BIBREF17 , BIBREF18 , BIBREF8   The training set has 89,042 sentence pairs, and the test set has 100 pairs  WikiLarge is also from Wikipedia corpus whose training set contains 296,402 sentence pairs BIBREF19 , BIBREF20   WikiLarge includes 8 (reference) simplifications for 2,359 sentences split into 2,000 for development and 359 for testing 
Metrics  Three metrics in text simplification are chosen in this paper  BLEU BIBREF5 is one traditional machine translation metric to assess the degree to which translated simplifications differed from reference simplifications  FKGL measures the readability of the output BIBREF23   A small FKGL represents simpler output  SARI is a recent text-simplification metric by comparing the output against the source and reference simplifications BIBREF20  
We evaluate the output of all systems using human evaluation  The metric is denoted as Simplicity BIBREF8   The three non-native fluent English speakers are shown reference sentences and output sentences  They are asked whether the output sentence is much simpler (+2), somewhat simpler (+1), equally (0), somewhat more difficult (-1), and much more difficult (-2) than the reference sentence 
Methods  We use OpenNMT BIBREF24 as the implementation of the NMT system for all experiments BIBREF5   We generally follow the default settings and training procedure described by Klein et al (2017)  We replace out-of-vocabulary words with a special UNK symbol  At prediction time, we replace UNK words with the highest probability score from the attention layer  OpenNMT system used on parallel data is the baseline system  To obtain a synthetic parallel training set, we back-translate a random sample of 100K sentences from the collected simplified corpora  OpenNMT used on parallel data and synthetic data is our model  The benchmarks are run on a Intel(R) Core(TM) i7-5930K CPU@3 50GHz, 32GB Mem, trained on 1 GPU GeForce GTX 1080 (Pascal) with CUDA v  8 0 
We choose three statistical text simplification systems  PBMT-R is a phrase-based method with a reranking post-processing step BIBREF18   Hybrid performs sentence splitting and deletion operations based on discourse representation structures, and then simplifies sentences with PBMT-R BIBREF25   SBMT-SARI BIBREF19 is syntax-based translation model using PPDB paraphrase database BIBREF26 and modifies tuning function (using SARI)  We choose two neural text simplification systems  NMT is a basic attention-based encoder-decoder model which uses OpenNMT framework to train with two LSTM layers, hidden states of size 500 and 500 hidden units, SGD optimizer, and a dropout rate of 0 3 BIBREF8   Dress is an encoder-decoder model coupled with a deep reinforcement learning framework, and the parameters are chosen according to the original paper BIBREF20   For the experiments with synthetic parallel data, we back-translate a random sample of 60 000 sentences from the collected simplified sentences into ordinary sentences  Our model is trained on synthetic data and the available parallel data, denoted as NMT+synthetic 
Results  Table 1 shows the results of all models on WikiLarge dataset  We can see that our method (NMT+synthetic) can obtain higher BLEU, lower FKGL and high SARI compared with other models, except Dress on FKGL and SBMT-SARI on SARI  It verified that including synthetic data during training is very effective, and yields an improvement over our baseline NMF by 2 11 BLEU, 1 7 FKGL and 1 07 SARI  We also substantially outperform Dress, who previously reported SOTA result  The results of our human evaluation using Simplicity are also presented in Table 1  NMT on synthetic data is significantly better than PBMT-R, Dress, and SBMT-SARI on Simplicity  It indicates that our method with simplified data is effective at creating simpler output 
Results on WikiSmall dataset are shown in Table 2  We see substantial improvements (6 37 BLEU) than NMT from adding simplified training data with synthetic ordinary sentences  Compared with statistical machine translation models (PBMT-R, Hybrid, SBMT-SARI), our method (NMT+synthetic) still have better results, but slightly worse FKGL and SARI  Similar to the results in WikiLarge, the results of our human evaluation using Simplicity outperforms the other models  In conclusion, Our method produces better results comparing with the baselines, which demonstrates the effectiveness of adding simplified training data 
Conclusion
In this paper, we propose one simple method to use simplified corpora during training of NMT systems, with no changes to the network architecture  In the experiments on two datasets, we achieve substantial gains in all tasks, and new SOTA results, via back-translation of simplified sentences into the ordinary sentences, and treating this synthetic data as additional training data  Because we do not change the neural network architecture to integrate simplified corpora, our method can be easily applied to other Neural Text Simplification (NTS) systems  We expect that the effectiveness of our method not only varies with the quality of the NTS system used for back-translation, but also depends on the amount of available parallel and simplified corpora  In the paper, we have only utilized data from Wikipedia for simplified sentences  In the future, many other text sources are available and the impact of not only size, but also of domain should be investigated 
Context 2: Introduction
Question answering (QA) has been a blooming research field for the last decade  Selection-based QA implies a family of tasks that find answer contexts from large data given questions in natural language  Three tasks have been proposed for selection-based QA  Given a document, answer extraction BIBREF0 , BIBREF1 finds answer phrases whereas answer selection BIBREF2 , BIBREF3 , BIBREF4 , BIBREF5 and answer triggering BIBREF6 , BIBREF7 find answer sentences instead, although the presence of the answer context is not assumed within the provided document for answer triggering but it is for the other two tasks  Recently, various QA tasks that are not selection-based have been proposed BIBREF8 , BIBREF9 , BIBREF10 , BIBREF11 ; however, selection-based QA remains still important because of its practical value to real applications (e g , IBM Watson, MIT Start) 
Several datasets have been released for selection-based QA  wang:07a created the QASent dataset consisting of 277 questions, which has been widely used for benchmarking the answer selection task  feng:15a presented InsuranceQA comprising 16K+ questions on insurance contexts  yang:15a introduced WikiQA for answer selection and triggering  jurczyk:16 created SelQA for large real-scale answer triggering  rajpurkar2016squad presented SQuAD for answer extraction and selection as well as for reading comprehension  Finally, morales-EtAl:2016:EMNLP2016 provided InfoboxQA for answer selection 
These corpora make it possible to evaluate the robustness of statistical question answering learning  Although all of these corpora target on selection-based QA, they are designed for different purposes such that it is important to understand the nature of these corpora so a better use of them can be made  In this paper, we make both intrinsic and extrinsic analyses of four latest corpora based on Wikipedia, WikiQA, SelQA, SQuAD, and InfoboxQA  We first give a thorough intrinsic analysis regarding contextual similarities, question types, and answer categories (Section SECREF2 )  We then map questions in all corpora to the current version of English Wikipedia and benchmark another selection-based QA task, answer retrieval (Section SECREF3 )  Finally, we present an extrinsic analysis through a set of experiments cross-testing these corpora using a convolutional neural network architecture (Section SECREF4 ) 
Intrinsic Analysis
Four publicly available corpora are selected for our analysis  These corpora are based on Wikipedia, so more comparable than the others, and have already been used for the evaluation of several QA systems 
WikiQA BIBREF6 comprises questions selected from the Bing search queries, where user click data give the questions and their corresponding Wikipedia articles  The abstracts of these articles are then extracted to create answer candidates  The assumption is made that if many queries lead to the same article, it must contain the answer context; however, this assumption fails for some occasions, which makes this dataset more challenging  Since the existence of answer contexts is not guaranteed in this task, it is called answer triggering instead of answer selection 
SelQA BIBREF7 is a product of five annotation tasks through crowdsourcing  It consists of about 8K questions where a half of the questions are paraphrased from the other half, aiming to reduce contextual similarities between questions and answers  Each question is associated with a section in Wikipedia where the answer context is guaranteed, and also with five sections selected from the entire Wikipedia where the selection is made by the Lucene search engine  This second dataset does not assume the existence of the answer context, so can be used for the evaluation of answer triggering 
SQuAD BIBREF12 presents 107K+ crowdsourced questions on 536 Wikipedia articles, where the answer contexts are guaranteed to exist within the provided paragraph  It contains annotation of answer phrases as well as the pointers to the sentences including the answer phrases; thus, it can be used for both answer extraction and selection  This corpus also provides human accuracy on those questions, setting up a reasonable upper bound for machines  To avoid overfitting, the evaluation set is not publicly available although system outputs can be evaluated by their provided script 
InfoboxQA BIBREF13 gives 15K+ questions based on the infoboxes from 150 articles in Wikipedia  Each question is crowdsourced and associated with an infobox, where each line of the infobox is considered an answer candidate  This corpus emphasizes the gravity of infoboxes, which summary arguably the most commonly asked information about those articles  Although the nature of this corpus is different from the others, it can also be used to evaluate answer selection 
Analysis
All corpora provide datasets/splits for answer selection, whereas only (WikiQA, SQuAD) and (WikiQA, SelQA) provide datasets for answer extraction and answer triggering, respectively  SQuAD is much larger in size although questions in this corpus are often paraphrased multiple times  On the contrary, SQuAD's average candidates per question ( INLINEFORM0 ) is the smallest because SQuAD extracts answer candidates from paragraphs whereas the others extract them from sections or infoboxes that consist of bigger contexts  Although InfoboxQA is larger than WikiQA or SelQA, the number of token types ( INLINEFORM1 ) in InfoboxQA is smaller than those two, due to the repetitive nature of infoboxes 
All corpora show similar average answer candidate lengths ( INLINEFORM0 ), except for InfoboxQA where each line in the infobox is considered a candidate  SelQA and SQuAD show similar average question lengths ( INLINEFORM1 ) because of the similarity between their annotation schemes  It is not surprising that WikiQA's average question length is the smallest, considering their questions are taken from search queries  InfoboxQA's average question length is relatively small, due to the restricted information that can be asked from the infoboxes  InfoboxQA and WikiQA show the least question-answer word overlaps over questions and answers ( INLINEFORM2 and INLINEFORM3 in Table TABREF2 ), respectively  In terms of the F1-score for overlapping words ( INLINEFORM4 ), SQuAD gives the least portion of overlaps between question-answer pairs although WikiQA comes very close 
Fig

ground_truth: For the WikiLarge dataset, the improvement over baseline NMT is 2.11 BLEU, 1.7 FKGL and 1.07 SARI.
For the WikiSmall dataset, the improvement over baseline NMT is  8.37 BLEU.

6.37 BLEU

prompt_front: You are given a scientific article and a question. Answer the question as concisely as you can, using a single phrase or sentence if possible. If the question cannot be answered based on the information in the article, write "unanswerable". If the question is a yes/no question, answer "yes", "no", or "unanswerable". Do not provide any explanation.

Please answer the questions based on the text provided below. Do they employ their indexing-based method to create a sample of a QA Wikipedia dataset?
Context 2:  FIGREF4 shows the distributions of seven question types grouped deterministically from the lexicons  Although these corpora have been independently developed, a general trend is found, where the what question type dominates, followed by how and who, followed by when and where, and so on 
Fig  FIGREF6 shows the distributions of answer categories automatically classified by our Convolutional Neural Network model trained on the data distributed by li:02a  Interestingly, each corpus focuses on different categories, Numeric for WikiQA and SelQA, Entity for SQuAD, and Person for InfoboxQA, which gives enough diversities for statistical learning to build robust models 
Answer Retrieval
This section describes another selection-based QA task, called answer retrieval, that finds the answer context from a larger dataset, the entire Wikipedia  SQuAD provides no mapping of the answer contexts to Wikipedia, whereas WikiQA and SelQA provide mappings; however, their data do not come from the same version of Wikipedia  We propose an automatic way of mapping the answer contexts from all corpora to the same version of Wikipeda so they can be coherently used for answer retrieval 
Each paragraph in Wikipedia is first indexed by Lucene using {1,2,3}-grams, where the paragraphs are separated by WikiExtractor and segmented by NLP4J (28 7M+ paragraphs are indexed)  Each answer sentence from the corpora in Table TABREF3 is then queried to Lucene, and the top-5 ranked paragraphs are retrieved  The cosine similarity between each sentence in these paragraphs and the answer sentence is measured for INLINEFORM0 -grams, say INLINEFORM1   A weight is assigned to each INLINEFORM2 -gram score, say INLINEFORM3 , and the weighted sum is measured: INLINEFORM4   The fixed weights of INLINEFORM5 are used for our experiments, which can be improved 
If there exists a sentence whose INLINEFORM0 , the paragraph consisting of that sentence is considered the silver-standard answer passage  Table TABREF3 shows how robust these silver-standard passages are based on human judgement ( INLINEFORM1 ) and how many passages are collected ( INLINEFORM2 ) for INLINEFORM3 , where the human judgement is performed on 50 random samples for each case  For answer retrieval, a dataset is created by INLINEFORM4 , which gives INLINEFORM5 accuracy and INLINEFORM6 coverage, respectively  Finally, each question is queried to Lucene and the top- INLINEFORM7 paragraphs are retrieved from the entire Wikipedia  If the answer sentence exists within those retrieved paragraphs according to the silver-standard, it is considered correct 
Finding a paragraph that includes the answer context out of the entire Wikipedia is an extremely difficult task (128 7M)  The last row of Table TABREF3 shows results from answer retrieval  Given INLINEFORM0 , SelQA and SQuAD show about 34% and 35% accuracy, which are reasonable  However, WikiQA shows a significantly lower accuracy of 12 47%; this is because the questions in WikiQA is about twice shorter than the questions in the other corpora such that not enough lexicons can be extracted from these questions for the Lucene search 
Answer Selection
Answer selection is evaluated by two metrics, mean average precision (MAP) and mean reciprocal rank (MRR)  The bigram CNN introduced by yu:14a is used to generate all the results in Table TABREF11 , where models are trained on either single or combined datasets  Clearly, the questions in WikiQA are the most challenging, and adding more training data from the other corpora hurts accuracy due to the uniqueness of query-based questions in this corpus  The best model is achieved by training on W+S+Q for SelQA; adding InfoboxQA hurts accuracy for SelQA although it gives a marginal gain for SQuAD  Just like WikiQA, InfoboxQA performs the best when it is trained on only itself  From our analysis, we suggest that to use models trained on WikiQA and InfoboxQA for short query-like questions, whereas to use ones trained on SelQA and SQuAD for long natural questions 
Answer Triggering
The results of INLINEFORM0 from the answer retrieval task in Section SECREF13 are used to create the datasets for answer triggering, where about 65% of the questions are not expected to find their answer contexts from the provided paragraphs for SelQA and SQuAD and 87 5% are not expected for WikiQA  Answer triggering is evaluated by the F1 scores as presented in Table TABREF11 , where three corpora are cross validated  The results on WikiQA are pretty low as expected from the poor accuracy on the answer retrieval task  Training on SelQA gives the best models for both WikiQA and SelQA  Training on SQuAD gives the best model for SQuAD although the model trained on SelQA is comparable  Since the answer triggering datasets are about 5 times larger than the answer selection datasets, it is computationally too expensive to combine all data for training  We plan to find a strong machine to perform this experiment in near future 
Related work
Lately, several deep learning approaches have been proposed for question answering  yu:14a presented a CNN model that recognizes the semantic similarity between two sentences  wang-nyberg:2015:ACL-IJCNLP presented a stacked bidirectional LSTM approach to read words in sequence, then outputs their similarity scores  feng:15a applied a general deep learning framework to non-factoid question answering  santos:16a introduced an attentive pooling mechanism that led to further improvements in selection-based QA 
Conclusion
We present a comprehensive comparison study of the existing corpora for selection-based question answering  Our intrinsic analysis provides a better understanding of the uniqueness or similarity between these corpora  Our extrinsic analysis shows the strength or weakness of combining these corpora together for statistical learning  Additionally, we create a silver-standard dataset for answer retrieval and triggering, which will be publicly available  In the future, we will explore different ways of improving the quality of our silver-standard datasets by fine-tuning the hyper-parameters 
Context 3: Introduction
Understanding the emotions expressed in a text or message is of high relevance nowadays  Companies are interested in this to get an understanding of the sentiment of their current customers regarding their products and the sentiment of their potential customers to attract new ones  Moreover, changes in a product or a company may also affect the sentiment of a customer  However, the intensity of an emotion is crucial in determining the urgency and importance of that sentiment  If someone is only slightly happy about a product, is a customer willing to buy it again? Conversely, if someone is very angry about customer service, his or her complaint might be given priority over somewhat milder complaints 
BIBREF0 present four tasks in which systems have to automatically determine the intensity of emotions (EI) or the intensity of the sentiment (Valence) of tweets in the languages English, Arabic, and Spanish  The goal is to either predict a continuous regression (reg) value or to do ordinal classification (oc) based on a number of predefined categories  The EI tasks have separate training sets for four different emotions: anger, fear, joy and sadness  Due to the large number of subtasks and the fact that this language does not have many resources readily available, we only focus on the Spanish subtasks  Our work makes the following contributions:
Our submissions ranked second (EI-Reg), second (EI-Oc), fourth (V-Reg) and fifth (V-Oc), demonstrating that the proposed method is accurate in automatically determining the intensity of emotions and sentiment of Spanish tweets  This paper will first focus on the datasets, the data generation procedure, and the techniques and tools used  Then we present the results in detail, after which we perform a small error analysis on the largest mistakes our model made  We conclude with some possible ideas for future work 
Data
For each task, the training data that was made available by the organizers is used, which is a selection of tweets with for each tweet a label describing the intensity of the emotion or sentiment BIBREF1   Links and usernames were replaced by the general tokens URL and @username, after which the tweets were tokenized by using TweetTokenizer  All text was lowercased  In a post-processing step, it was ensured that each emoji is tokenized as a single token 
Word Embeddings
To be able to train word embeddings, Spanish tweets were scraped between November 8, 2017 and January 12, 2018  We chose to create our own embeddings instead of using pre-trained embeddings, because this way the embeddings would resemble the provided data set: both are based on Twitter data  Added to this set was the Affect in Tweets Distant Supervision Corpus (DISC) made available by the organizers BIBREF0 and a set of 4 1 million tweets from 2015, obtained from BIBREF2   After removing duplicate tweets and tweets with fewer than ten tokens, this resulted in a set of 58 7 million tweets, containing 1 1 billion tokens  The tweets were preprocessed using the method described in Section SECREF6   The word embeddings were created using word2vec in the gensim library BIBREF3 , using CBOW, a window size of 40 and a minimum count of 5  The feature vectors for each tweet were then created by using the AffectiveTweets WEKA package BIBREF4  
Translating Lexicons
Most lexical resources for sentiment analysis are in English  To still be able to benefit from these sources, the lexicons in the AffectiveTweets package were translated to Spanish, using the machine translation platform Apertium BIBREF5  
All lexicons from the AffectiveTweets package were translated, except for SentiStrength  Instead of translating this lexicon, the English version was replaced by the Spanish variant made available by BIBREF6  
For each subtask, the optimal combination of lexicons was determined  This was done by first calculating the benefits of adding each lexicon individually, after which only beneficial lexicons were added until the score did not increase anymore (e g  after adding the best four lexicons the fifth one did not help anymore, so only four were added)  The tests were performed using a default SVM model, with the set of word embeddings described in the previous section  Each subtask thus uses a different set of lexicons (see Table TABREF1 for an overview of the lexicons used in our final ensemble)  For each subtask, this resulted in a (modest) increase on the development set, between 0 01 and 0 05 
Translating Data
The training set provided by BIBREF0 is not very large, so it was interesting to find a way to augment the training set  A possible method is to simply translate the datasets into other languages, leaving the labels intact  Since the present study focuses on Spanish tweets, all tweets from the English datasets were translated into Spanish  This new set of “Spanish” data was then added to our original training set  Again, the machine translation platform Apertium BIBREF5 was used for the translation of the datasets 
Algorithms Used
Three types of models were used in our system, a feed-forward neural network, an LSTM network and an SVM regressor  The neural nets were inspired by the work of Prayas BIBREF7 in the previous shared task  Different regression algorithms (e g  AdaBoost, XGBoost) were also tried due to the success of SeerNet BIBREF8 , but our study was not able to reproduce their results for Spanish 
For both the LSTM network and the feed-forward network, a parameter search was done for the number of layers, the number of nodes and dropout used  This was done for each subtask, i e  different tasks can have a different number of layers  All models were implemented using Keras BIBREF9   After the best parameter settings were found, the results of 10 system runs to produce our predictions were averaged (note that this is different from averaging our different type of models in Section SECREF16 )  For the SVM (implemented in scikit-learn BIBREF10 ), the RBF kernel was used and a parameter search was conducted for epsilon  Detailed parameter settings for each subtask are shown in Table TABREF12   Each parameter search was performed using 10-fold cross validation, as to not overfit on the development set 
Semi-supervised Learning
One of the aims of this study was to see if using semi-supervised learning is beneficial for emotion intensity tasks  For this purpose, the DISC BIBREF0 corpus was used  This corpus was created by querying certain emotion-related words, which makes it very suitable as a semi-supervised corpus  However, the specific emotion the tweet belonged to was not made public  Therefore, a method was applied to automatically assign the tweets to an emotion by comparing our scraped tweets to this new data set 
First, in an attempt to obtain the query-terms, we selected the 100 words which occurred most frequently in the DISC corpus, in comparison with their frequencies in our own scraped tweets corpus  Words that were clearly not indicators of emotion were removed  The rest was annotated per emotion or removed if it was unclear to which emotion the word belonged  This allowed us to create silver datasets per emotion, assigning tweets to an emotion if an annotated emotion-word occurred in the tweet

ground_truth: Yes

No

prompt_front: You are given a scientific article and a question. Answer the question as concisely as you can, using a single phrase or sentence if possible. If the question cannot be answered based on the information in the article, write "unanswerable". If the question is a yes/no question, answer "yes", "no", or "unanswerable". Do not provide any explanation.

Please answer the questions based on the text provided below. How was the training data translated?
Context 3: 
Our semi-supervised approach is quite straightforward: first a model is trained on the training set and then this model is used to predict the labels of the silver data  This silver data is then simply added to our training set, after which the model is retrained  However, an extra step is applied to ensure that the silver data is of reasonable quality  Instead of training a single model initially, ten different models were trained which predict the labels of the silver instances  If the highest and lowest prediction do not differ more than a certain threshold the silver instance is maintained, otherwise it is discarded 
This results in two parameters that could be optimized: the threshold and the number of silver instances that would be added  This method can be applied to both the LSTM and feed-forward networks that were used  An overview of the characteristics of our data set with the final parameter settings is shown in Table TABREF14   Usually, only a small subset of data was added to our training set, meaning that most of the silver data is not used in the experiments  Note that since only the emotions were annotated, this method is only applicable to the EI tasks 
Ensembling
To boost performance, the SVM, LSTM, and feed-forward models were combined into an ensemble  For both the LSTM and feed-forward approach, three different models were trained  The first model was trained on the training data (regular), the second model was trained on both the training and translated training data (translated) and the third one was trained on both the training data and the semi-supervised data (silver)  Due to the nature of the SVM algorithm, semi-supervised learning does not help, so only the regular and translated model were trained in this case  This results in 8 different models per subtask  Note that for the valence tasks no silver training data was obtained, meaning that for those tasks the semi-supervised models could not be used 
Per task, the LSTM and feed-forward model's predictions were averaged over 10 prediction runs  Subsequently, the predictions of all individual models were combined into an average  Finally, models were removed from the ensemble in a stepwise manner if the removal increased the average score  This was done based on their original scores, i e  starting out by trying to remove the worst individual model and working our way up to the best model  We only consider it an increase in score if the difference is larger than 0 002 (i e  the difference between 0 716 and 0 718)  If at some point the score does not increase and we are therefore unable to remove a model, the process is stopped and our best ensemble of models has been found  This process uses the scores on the development set of different combinations of models  Note that this means that the ensembles for different subtasks can contain different sets of models  The final model selections can be found in Table TABREF17  
Results and Discussion
Table TABREF18 shows the results on the development set of all individuals models, distinguishing the three types of training: regular (r), translated (t) and semi-supervised (s)  In Tables TABREF17 and TABREF18 , the letter behind each model (e g  SVM-r, LSTM-r) corresponds to the type of training used  Comparing the regular and translated columns for the three algorithms, it shows that in 22 out of 30 cases, using translated instances as extra training data resulted in an improvement  For the semi-supervised learning approach, an improvement is found in 15 out of 16 cases  Moreover, our best individual model for each subtask (bolded scores in Table TABREF18 ) is always either a translated or semi-supervised model  Table TABREF18 also shows that, in general, our feed-forward network obtained the best results, having the highest F-score for 8 out of 10 subtasks 
However, Table TABREF19 shows that these scores can still be improved by averaging or ensembling the individual models  On the dev set, averaging our 8 individual models results in a better score for 8 out of 10 subtasks, while creating an ensemble beats all of the individual models as well as the average for each subtask  On the test set, however, only a small increase in score (if any) is found for stepwise ensembling, compared to averaging  Even though the results do not get worse, we cannot conclude that stepwise ensembling is a better method than simply averaging 
Our official scores (column Ens Test in Table TABREF19 ) have placed us second (EI-Reg, EI-Oc), fourth (V-Reg) and fifth (V-Oc) on the SemEval AIT-2018 leaderboard  However, it is evident that the results obtained on the test set are not always in line with those achieved on the development set  Especially on the anger subtask for both EI-Reg and EI-Oc, the scores are considerably lower on the test set in comparison with the results on the development set  Therefore, a small error analysis was performed on the instances where our final model made the largest errors 
Error Analysis
Due to some large differences between our results on the dev and test set of this task, we performed a small error analysis in order to see what caused these differences  For EI-Reg-anger, the gold labels were compared to our own predictions, and we manually checked 50 instances for which our system made the largest errors 
Some examples that were indicative of the shortcomings of our system are shown in Table TABREF20   First of all, our system did not take into account capitalization  The implications of this are shown in the first sentence, where capitalization intensifies the emotion used in the sentence  In the second sentence, the name Imperator Furiosa is not understood  Since our texts were lowercased, our system was unable to capture the named entity and thought the sentence was about an angry emperor instead  In the third sentence, our system fails to capture that when you are so angry that it makes you laugh, it results in a reduced intensity of the angriness  Finally, in the fourth sentence, it is the figurative language me infla la vena (it inflates my vein) that the system is not able to understand 
The first two error-categories might be solved by including smart features regarding capitalization and named entity recognition  However, the last two categories are problems of natural language understanding and will be very difficult to fix 
Conclusion
To conclude, the present study described our submission for the Semeval 2018 Shared Task on Affect in Tweets  We participated in four Spanish subtasks and our submissions ranked second, second, fourth and fifth place  Our study aimed to investigate whether the automatic generation of additional training data through translation and semi-supervised learning, as well as the creation of stepwise ensembles, increase the performance of our Spanish-language models  Strong support was found for the translation and semi-supervised learning approaches; our best models for all subtasks use either one of these approaches  These results suggest that both of these additional data resources are beneficial when determining emotion intensity (for Spanish)  However, the creation of a stepwise ensemble from the best models did not result in better performance compared to simply averaging the models  In addition, some signs of overfitting on the dev set were found  In future work, we would like to apply the methods (translation and semi-supervised learning) used on Spanish on other low-resource languages and potentially also on other tasks 

ground_truth: using the machine translation platform Apertium 

machine translation platform Apertium BIBREF5