Aspect-based Sentiment Analysis
- Aspect based Sentiment Analysis:Aspect-based sentiment analysis is a text analysis technique that breaks down text into aspects (attributes or components of a product or service), and then allocates each one a sentiment level (positive, negative or neutral).
- Example:Great food but the service was dreadful. So delicious was the noodles but terrible vegetables.
- syntax information, task-related syntatic structures is the key.
Aspect-Oriented Dependency Tree
- For input sentences, apply a dependency parser to obtain its dependency tree, rij is the relation from node i to node j.
- place the target aspect at the root
- set the nodes with direct connections to the aspect as the children.
- other relations are retained, instead introduce a virtual relation n:con from the aspect to each corresponding nodes, where n represents the distance between two nodes. If one sentence include multi-aspects, build a unique tree for each aspect
Relational Graph Attention Network
- encode the dependency trees with its labeled edges
- update each node representation by aggregating neighborhood node representations.
- extend the original GAT with additional relational heads. We use these heads as gates to control influence fluence from neighborhood nodes. First map the dependency relations to vector.
Model Training
- BiLSTM encode tree nodes as hi, another BiLSTM encode aspect words as , its average hidden state as the initial representation ha0 of this root.
Baseline Methods
- Syntax-aware models
- Attention-based models
- other recent methods