refactor optimal retention to minimize workload per memorization & fix progress goes backwards

[L-M-Sherlock]

I will update the dependency after the following PR is merged:

• Feat/minimal workload for optimal retention open-spaced-repetition/fsrs-rs#165

Help wanted:

• brief introduction of this feature.
• notice user that desired retention < optimal retention is worse than desired retention > optimal retention because the former means less memorization & more workload and the latter means more memorization & more workload.
• notice user that the setting of Maximum interval would affect the result.

@Expertium, could you help me?

Edit:

This PR also contains:

• Fix/progress goes backwards open-spaced-repetition/fsrs-rs#166
• Minor tweaks to #166 open-spaced-repetition/fsrs-rs#167

[Expertium]

Perhaps just add a short text description under "Compute optimal retention (experimental)"? The problem is how to make it short and concise.

Setting desired retention lower than optimal is not recommended. Also, changing the maximum interval will impact the result.

EDIT: on second thought, max. interval should be a setting under "Compute optimal retention (experimental)", for 2 reasons:

1. It makes it way more clear than any text that max. interval affects the result.
2. Some users may get too carried away with playing with this new option and forget to revert max. interval to its initial value.

[L-M-Sherlock]

EDIT: on second thought, max. interval should be a setting under "Compute optimal retention (experimental)", for 2 reasons:

These two settings are in the same section and their positions have been very near.

[Expertium]

Ok, then just add a text message: Setting desired retention lower than optimal is not recommended. Additionally, changing the maximum interval will affect the result.

The problem is that having a setting that affects the result of "Compute optimal retention" outside of, well, "Compute optimal retention", is weird.

[dae]

notice user that desired retention < optimal retention is worse than desired retention > optimal retention because the former means less memorization & more workload and the latter means more memorization & more workload.

To confirm I understand you correctly, do you mean:

• If the computed optimal retention (OR) is < desired retention (DR), we should say something like "Your desired retention is below optimal. Increasing it is recommended"?
• If OR >= DR, we show no message?

The problem is that having a setting that affects the result of "Compute optimal retention" outside of, well, "Compute optimal retention", is weird.

It's already using a bunch of other information from the collection such as pass rates and the configured parameters. Do we really need to treat max interval differently?

[L-M-Sherlock]

• If the computed optimal retention (OR) is < desired retention (DR), we should say something like "Your desired retention is below optimal. Increasing it is recommended"?

Do you mean DR < OR? If so, it's what I mean.

[dae]

A question for release planning: are there many other changes you'd like to make to FSRS before 24.04 releases? Would a stable release in 2-3 weeks after one more rc work, or would you like more time?

[L-M-Sherlock]

There will not be many more changes, except that currently I'm trying to optimize the performance of optimal_retention, but there has been no progress so far.

[dae]

Thanks guys!

[Expertium]

Too bad I thought about this so late, but still: it's not obvious at all what "optimal" means, so I think there should be a short sentence saying something like "This value of retention minimizes the amount of studying per day" or something along those lines.

[L-M-Sherlock]

it's not obvious at all what "optimal" means

I'm writing a wiki page for it. Could you help me? Here is the link: https://github.com/open-spaced-repetition/fsrs4anki/wiki/The-optimal-retention

[Expertium]

I meant that it should be clarified within Anki itself.

[Expertium]

@user1823 here's another article that you can help us with, if you want to: https://github.com/open-spaced-repetition/fsrs4anki/wiki/The-Optimal-Retention

[user1823]

I will take a look at it later.