mu — Advanced Unix-style Spaced Repetition System

After becoming increasingly dissatisfied with my workflow in Anki, which I used for studying, I decided to write mu, which essentially replicates the functionality of Anki, but is more "Unix-style":

• A text-based, shell-like interface instead of a GUI: I hope I need not convince you that using your keyboard is faster than using your mouse, and as such (at least for "advanced users") programs centered around text (which is most programs) ought to be terminal-based.
• First-class TeX integration: While Anki does support TeX, it feels like a hack with all sorts of issues with diagrams and so on. mu is literally just opening a PDF viewer (e.g. in some sort of presentation mode, as zathura implements) for viewing card, and will therefore just view your rendered TeX file.
• Flashcards sit in the file system instead of a database: One major issue with Anki is that flashcards are stored in a database file, which means in particular that you cannot keep your cards neatly in a version control system.
• Editing is done in your editor of choice: Somewhat adjacent to the previous point, I found that the Anki editor encouraged laziness, because I could not use my editor of choice when creating and editing cards. When I have increased control, I care more and as a result I don't get a deck that is just thrown together.

Technical details

mu is based on SM2 algorithms, specifically Anki's version of the algorithm (most of the defaults are shamelessly stolen from Anki), with the exception of one important feature: adaptivity.

Adaptivity means that each tag is assigned a "familiarity" (which can be thought of as a tag-level E-factor), which is adjusted based on your performance on the cards in the tags. When answering well on a card in some tag, this factor increases, causing the intervals of cards with the tag to increase more after review. It reflects the fact that you may be more familiar with one subject than another.

To-do

• Make interactive cards easier: While the .mu format implements sh: followed by a command for specifying an arbitrary command (e.g. some program doing cloze) instead of a PDF, this is not implemented by mkmu.
  • Implement a cloze program and other interactive flashcard styles.
• Heatmap of activity.
• Align rt table.
• Add command to output sorted familiarities.
• Better, non-automated control over intervals:
  • Postponing cards

Usage

You have a directory like the following:

├── gauss_bonnett.tex
├── schrodinger_equation.tex
└── yoneda_lemma.tex

where each .tex file starts with something like:

%tags: Fact, Noncourse
%priority: 3

where tags are some user chosen, arbitrarily named strings separated by commas, and priority is a number 1-5, with a higher number meaning more important (both of these are used in determining calculation of intervals).

You can then run mkmu, which crawls directories (and subdirectories) and compiles the TeX files using the latexmk build tool. The resulting files are placed in the deck directory.

After that, you may run mu in the directory containing the deck/ directory, which starts mu, entering into a shell-like program that looks like this (run help to see list of commands):

——— card 'grassmanian' ———
file:      grassmanian.pdf
tags:      Fact, W5
priority:  2
(opening grassmanian.pdf)
——— new intervals ———
fail:  30m
hard:  30m
okay:  30m
good:  1d
easy:  1d
D:0 N:9 >> good

This opens the TeX files, containing the flashcards. The default viewer is zathura, but can be set by changing the MU_PDF_VIEWER environment variable.