Gnosis (γνῶσις), pronounced “noh-sis”, meaning knowledge in Greek, is a spaced repetition system implementation for note taking and self testing. Notes are organized in a Question/Answer/Explanation format and reviewed at spaced intervals, determined by the success or failure to recall the answer.

The goal of Gnosis is to enhance memory retention through active recall. To achieve optimal results, users review Gnosis notes by writing out the answers.

Above all, Gnosis aspires to be a versatile instrument of learning.

This manual is written for Gnosis version 0.3.1, released on 2024-07-15.

1 Introduction

Before reading this manual, it’s recommended you first try out gnosis-demo

Gnosis, is a spaced repetition system for note taking & self testing, where notes are taken in a Question/Answer/Explanation format & reviewed in spaced intervals, determined by the success or failure to recall a given answer.

Gnosis implements a highly customizable algorithm, inspired by SM-2. Gnosis algorithm does not use user’s subjective rating of a note to determine the next review interval, but instead uses the user’s success or failure in recalling the answer of a note. Read more on gnosis-algorithm

2 Adding notes

Creating notes for gnosis can be done interactively with:

M-x gnosis-add-note

When it comes to adding images, you can select images that are inside gnosis-images-dir. For adjusting image size, refer to Customization

3 Note Types

3.1 Cloze

A cloze note type is a format where you create sentences or paragraphs with “missing” words. A fill-in-the-blanks question.

You can create a cloze note type using M-x gnosis-add-note and selecting Cloze, the question should be formatted like this:

{c1:Cyproheptadine::drug name} is a(n) {c2:5-HT2} receptor antagonist used to treat {c2:serotonin syndrome}

You can also format clozes like Anki if you so prefer; e.g {{c1::Cyproheptadine::drug name}}

  • For each cX-tag there will be created a cloze type note, the above example creates 2 cloze type notes.

  • Each cX tag can have multiple clozes, but each cloze must be a UNIQUE word (or a unique combination of words) in given note.

  • You can use the keyword :: to indicate a hint.

You can remove the guidance string by adjusting gnosis-cloze-guidance.

3.2 MC-Cloze

A MC-Cloze (Multiple Choice Cloze) is a fill-in-the-blank note, but unlike cloze note type the user is prompted to select an option instead of typing an answer.

You can create multiple notes from one input, but each note can only have one cloze. The first option will always be the right answer (will be randomized in the database), separated by the rest of the answer by gnosis-mc-cloze-separator (default value is “&&”), and a note will be generated from each cloze.

Example:

The greatest text editor is Emacs&&Vim&&Helix

When customizing gnosis-mc-cloze=separator pay attention to not use values that would mess up with regex functions.

3.3 MCQ (Multiple Choice Question)

A MCQ note type, as the name suggests, is a multiple choice question.

The stem field (question) is separated by the options (choices) via gnosis-mcq-separator, each option is separated by gnosis-mcq-option-separator.

You can remove the guidance string by adjusting gnosis-mcq-guidance.

3.4 Basic Type

Basic note type is a simple question/answer note, where the user first sees a “main” part, which is usually a question, and he is prompted to input the answer.

3.5 Double

Double note type, is essentially a note that generates 2 basic notes. The second one reverses question/answer.

Ideal for vocabulary acquisition notes.

3.6 y-or-n

y-or-n (yes or no) note type, user is presented with a question and prompted to enter character “y” or “n”.

When using the hidden function gnosis-add-note--y-or-n, note that the ANSWER must be either 121 (y) or 110 (n), as those correspond to the character values used to represent them.

4 Customization

4.1 Image size

Adjust image size using gnosis-image-height & gnosis-image-width

Example:

(setf gnosis-image-height 300
      gnosis-image-width 300)

4.2 Typos | String Comparison

You can adjust gnosis-string-difference, this is a threshold value for string comparison that determines the maximum acceptable Levenshtein distance between two strings, which identifies their similarity

Let’s illustrate with an example:

(setf gnosis-string-difference 1)

In this scenario, we set gnosis-string-difference to 1. This implies that two strings will be recognized as similar if they exhibit a difference of at most one character edit.

To demonstrate, ’example’ and ’examples’ will be recognized as similar, considering that the latter involves just one additional character."

5 Gnosis Algorithm

Each gnosis note has an ef (easiness factor), which is a list of 3 values. The last value is the total ef for a note, which will be used to determine the next interval upon a successful answer recall, the second value is the ef-decrease value, this value will be subtracted from the the total ef upon failure to recall the answer of a note, the first value is the ef increase, will be added to the total ef upon a successful recall.

Each gnosis deck has gnosis-algorithm-ef-threshold, it’s an integer value that refers to the consecutive success or failures to recall an answer. Upon reaching the threshold, gnosis-algorithm-ef-decrease or gnosis-algorithm-ef-increase will be applied to the ef-increase or ef-decrease of note.

You can customize deck specific algorithm values using gnosis-dashboard.

5.1 Initial Interval

The default initial interval is defined at gnosis-algorithm-interval, you can define a custom initial interval for each deck as well.

gnosis-algorithm-interval is a list of 2 numbers, representing the first two initial intervals for successful reviews.

Example:

(setq gnosis-algorithm-interval '(0 1))

Using the above example, after first successfully reviewing a note, you will see it again in the next review session, if you successfully review said note again, the next review will be tomorrow.

Upon failing to review a note without completing 2 successful reviews, you will have to review it again on the same day.

5.2 Easiness Factor

The gnosis-algorithm-ef is a list that consists of three items:

  1. Easiness factor increase value: Added to the easiness factor upon a successful review.

  2. Easiness factor decrease value: Subtracted from the total easiness factor upon a failed review.

  3. Total Easiness factor: Used to calculate the next interval.

How this is used:

Multiplies the last interval by the easiness factor after a successful review.

For example, upon a successful review, if the last review was 6 days ago with an easiness factor of 2.0, the next interval would be calculated as 6 * 2.0, and the next total easiness factor would be updated by adding the increase value 2.0 + <increase-value>.

Configuration example:

(setq gnosis-algorithm-ef '(0.30 0.25 1.3))

5.3 Forgetting Factor

gnosis-algorithm-ff is a floating number below 1.

Used to determine the next interval after an unsuccessful review.

Multiplied with the last interval to calculate the next interval. For example, if gnosis-algorithm-ff is set to 0.5 and the last interval was 6 days, the next interval will be 6 * 0.5 = 3 days.

Example configuration:

(setq gnosis-algorithm-ff 0.5)

You can set a custom gnosis-algorithm-ff for each deck as well.

6 Editing notes

  • Currently there are 2 ways for editing notes:
    • You can edit a note after review by pressing e
    • Open gnosis-dashboard with M-x gnosis-dashboard, find the note you want to edit and press e

7 Sync between devices

Gnosis uses git to maintain data integrity and facilitate synchronization across devices.

You will need to configure your remote manually.

Example:

cd ~/.emacs.d/gnosis # default location for gnosis
git init # After completing your first review session, a git repo should have been initialized automatically.
git remote add origin <remote_url>
git push --set-upstream origin master

You can interactively use gnosis-vc-push & gnosis-vc-pull. As the name suggests, they rely on vc to work properly.

Depending on your setup, vc might require an external package for the ssh passphrase dialog, such as x11-ssh-askpass.

To automatically push changes after a review session, add this to your configuration:

(setf gnosis-vc-auto-push t)
(gnosis-vc-pull) ;; Run vc-pull for gnosis on startup

8 Extending Gnosis

To make development and customization easier, gnosis comes with gnosis-test module, that should be used to create a custom database for testing.

To exit the testing environment, rerun M-x gnosis-test-start and then enter n (no) at the prompt “Start development env?”

8.1 Creating Custom Note Types

Creating custom note types for gnosis is a fairly simple thing to do

  • First add your NEW-TYPE to gnosis-note-types

    (add-to-list 'gnosis-note-types "new-note-type")

  • Create 2 functions; gnosis-add-note-TYPE & gnosis-add-note--TYPE

Each note type has a gnosis-add-note-TYPE that is used interactively & a “hidden function” gnosis-add-note--TYPE that handles all the logic.

Refer to gnosis-add-note-basic & gnosis-add-note--basic for a simple example of how this is done.

  • Create gnosis-review-TYPE

This function should handle the review process, displaying it’s contents and updating the database depending on the result of the review (fail/pass). Refer to gnosis-review-basic for an example of how this should be done.

  • Optionally, you might want to create your own custom gnosis-display functions