Maja Karasalo


FOI DSS at SemEval-2018 Task 1: Combining LSTM States, Embeddings, and Lexical Features for Affect Analysis
Maja Karasalo | Mattias Nilsson | Magnus Rosell | Ulrika Wickenberg Bolin
Proceedings of the 12th International Workshop on Semantic Evaluation

This paper describes the system used and results obtained for team FOI DSS at SemEval-2018 Task 1: Affect In Tweets. The team participated in all English language subtasks, with a method utilizing transfer learning from LSTM nets trained on large sentiment datasets combined with embeddings and lexical features. For four out of five subtasks, the system performed in the range of 92-95% of the winning systems, in terms of the competition metrics. Analysis of the results suggests that improved pre-processing and addition of more lexical features may further elevate performance.


Mama Edha at SemEval-2017 Task 8: Stance Classification with CNN and Rules
Marianela García Lozano | Hanna Lilja | Edward Tjörnhammar | Maja Karasalo
Proceedings of the 11th International Workshop on Semantic Evaluation (SemEval-2017)

For the competition SemEval-2017 we investigated the possibility of performing stance classification (support, deny, query or comment) for messages in Twitter conversation threads related to rumours. Stance classification is interesting since it can provide a basis for rumour veracity assessment. Our ensemble classification approach of combining convolutional neural networks with both automatic rule mining and manually written rules achieved a final accuracy of 74.9% on the competition’s test data set for Task 8A. To improve classification we also experimented with data relabeling and using the grammatical structure of the tweet contents for classification.