Editing SuperMemo (section)

=== Description of SM-2 algorithm ===

The first computer-based SuperMemo algorithm (SM-2)<ref name="Wozniak1990-SM2"/> tracks three properties for each card being studied:

* The repetition number '''n''', which is the number of times the card has been successfully recalled (meaning it was given a grade ≥ 3) in a row since the last time it was not.
* The easiness factor '''EF''', which loosely indicates how "easy" the card is (more precisely, it determines how quickly the inter-repetition interval grows). The initial value of '''EF''' is 2.5.
* The inter-repetition interval '''I''', which is the length of time (in days) SuperMemo will wait after the previous review before asking the user to review the card again.

Every time the user starts a review session, SuperMemo provides the user with the cards whose last review occurred at least '''I''' days ago. For each review, the user tries to recall the information and (after being shown the correct answer) specifies a grade '''q''' (from 0 to 5) indicating a self-evaluation the quality of their response, with each grade having the following meaning:

* 0: "Total blackout", complete failure to recall the information.
* 1: Incorrect response, but upon seeing the correct answer it felt familiar.
* 2: Incorrect response, but upon seeing the correct answer it seemed easy to remember.
* 3: Correct response, but required significant effort to recall.
* 4: Correct response, after some hesitation.
* 5: Correct response with perfect recall.

The following algorithm<ref>{{cite web |title=Super-Memo 2 Plugin for Super-Memo for Windows: Delphi Source Code |url=https://www.super-memory.com/english/ol/sm2source.htm |website=SuperMemo Articles |access-date=23 August 2021}}</ref> is then applied to update the three variables associated with the card:

 '''algorithm''' SM-2 '''is'''
     '''input:'''  user grade ''q''
             repetition number ''n''
             easiness factor ''EF''
             interval ''I''
     '''output:''' updated values of ''n'', ''EF'', and ''I''
 
     '''if''' ''q'' ≥ 3 ''(correct response)'' '''then'''
         '''if''' ''n'' = 0 '''then'''
             ''I'' ← 1
         '''else if''' ''n'' = 1 '''then'''
             ''I'' ← 6
         '''else'''
             ''I'' ← round(''I'' × ''EF'')
         '''end if'''
         increment ''n''
     '''else''' ''(incorrect response)''
         ''n'' ← 0
         ''I'' ← 1
     '''end if'''
     
     ''EF'' ← ''EF'' + (0.1 &minus; (5 &minus; ''q'') × (0.08 + (5 &minus; ''q'') × 0.02))
     '''if''' ''EF'' < 1.3 '''then'''
         ''EF'' ← 1.3
     '''end if'''
     
     '''return''' (''n'', ''EF'', ''I'')

After all scheduled reviews are complete, SuperMemo asks the user to re-review any cards they marked with a grade less than 4 repeatedly until they give a grade ≥ 4.