Alexandria

Alexandria brings mathematical knowledge to your fingertips. It provides full-text search for LaTeX documents.

What problem does Alexandria try to solve?

When working as a mathematician you will frequently be facing the problem of finding theorems or definitions that apply to the problem at hand. Sure, for commonly used theorems, Google will be all you will need. For more specialized knowledge, you can use use some full-text search solution for PDFs, so you can search a bunch of books or papers.

When you search for something containing the terms "closure" and "compact", a PDF based search might show you a page with those terms in close proximity. The matches will surely include the theorem you are looking for, but it could just as well be a page containing two theorems, one ending with "Hence, A is compact." and the one after that starting with "Let X be the closure of …".

Generally, you will have lots of false positive matches, where the search terms occur close together, but not as part of the same theorem. The problem, of course, is that PDF documents lack structure. A program reading a PDF document has no way of knowing where one theorem ends and the next one begins. A full-text search can only look for proximity, not for is part of the same theorem.

How is Alexandria different?

Alexandria does nothing more than a full-text search of some documents. Its advantage comes from the ability to have one document per theorem or definition. That way, if a match in a document is found, you have, by definition, found a theorem or definition that contains the search terms.

Each document has a type, and can contain tags. In addition, you can search by type, e.g. using type:definition, or tag, e.g. tag:topology tag:analysisc. You can also add a source annotation, which can also be searched.

How to interact with Alexandria

You can interact with Alexandria in two different ways:

• A command line interface, also called alexandria

  The CLI can be used to update the index, using alexandria -i or --index, print statistics using -S or --stats, or to query the Alexandria knowledge base by just calling alexandria followed by some terms you want to search for. Note that you might have to escape some characters, depending on your shell and its configuration.

• A web interface, alexandria-web.

  alexandria-web start a web server that listens on 127.0.0.1:41665. Visit that page with a web browser of your choice to use alexandria-web.

Search

Say you want to look up some definition from Hartshorne's Algebraic Geometry mentioning the Zariski topology. You could search for source:hartshorne tag:geometry type:definition zariski.

Dependencies

• github.com/ogier/pflag and github.com/blevesearch/bleve, which go get github.com/yzhs/alexandria will install automatically,
• XeLaTeX to create a PDF file from the LaTeX source, and
• imagemagick, more to convert the PDF file to a PNG image that can be shown in the browser.