Readme

README.md

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 # Search <img alt="Rust's Crab" width="25px" src="https://rustacean.net/assets/rustacean-flat-noshadow.png"/>
-Search engine written in Rust.
+
+Search engine written in Rust, based on an inverted index on disk.
+
+**Implementation status** 
+- [x] IO classes for writing and reading bit-streams;
+- [ ] Structure to hold the vocabulary;
+- [ ] Text preprocessing;
+- [ ] In-memory datasets index construction;
+- [ ] Disk-based partial index construction and merging;
+- [ ] Additional indexes to support things such as spelling correction.
+
+**References**
+- [Introduction to Information Retrieval - Christopher D. Manning, Prabhakar Raghavan and Hinrich Schütze](https://nlp.stanford.edu/IR-book/information-retrieval-book.html)