Terrier 4.0 represents a major update over the previous 3.6 release, adding significant new features, including:
- Real-time index structures to facilitate incremental indexing of new documents as over time
- Pluggable state-of-the-art index compression reduces the size of Terrier's index structures
- Learning-to-rank support enables out-of-the-box supervised ranking models, trained using state-of-the-art approaches such as LambdaMART
- A website search application is now provided, illustrating real-time crawling, indexing and retrieval within Terrier.