AniList, MyAnimeList and Fuzzy Logic

For those who are passionate of animation keeping track of all of animes watched can be a huge problem, particularly if you’re one of those guys that watch at least 50 series per year. Fortunately God gave us some fantastic websites on which we can create our own list of completed, watching, dropped and plan to watch animes and update it anytime we need, thus we can finally remember all of the things we’ve watched and constantly observing new series and old one we missed (and of course realizing that we’ve spent more than 100 days watching cartoons). But the most interesting feature those sites offer, the thing that is the core of this article, is the voting one; while most of the features are exactly the same in both AniList and MyAnimeList, the voting one differs: in MyAnimeList you can vote an anime with a number between 0 and 10 but only whole numbers are accepted while in AniList you can set your list to vote with numbers between 0 and 100 (only whole ones) or between 0,0 and 10 (only real numbers in the form \frac{n}{10}). Most of anime fans use MyAnimeList (from now on MAL) over AniList (AL) but I really think that AL voting system is better and then that the site deserve more attention than it currently have; why I thing that AL voting system is better? Because to me it’s based on a logic that’s better at formalizing the concept of liking a show.

Before diving into AL and MAL let’s suppose that a less powerful anime-list site exists: ClassicList (CL). On CL you have only two possible votes: 0 if you don’t like the show and 10 if you actually liked it. Let’s now think of a user of CL that:

  1. Likes Keroro
  2. Likes Selector Spread Wixoss
  3. Likes Keroro more than Selector Spread Wixoss
  4. Does not like Sword Art Online1

Compiling his list this user will face some problem because while it’s obvious that Keroro will get a 10 and Sword Art Online a 0 Wixoss‘s vote is problematic. He likes it but he likes it lesser than Keroro so giving it a 10 wouldn’t be right because that’s the same vote as Keroro, a series that he likes more than Wixoss; of course giving it a 0 wouldn’t work as well because he clearly likes Selector Spread Wixoss more than Sword Art Online. A site like CL will force you to decide only between animes you like and animes you don’t like and so it’s a very restrictive system since things like “I like A and B but A more than B” can’t be expressed on a CL list. This will probably make lots of users abandon the platform for a better one.

A similar thing happen in logic when we chose to use a many-valued logic over classical logic: in classical logic we have only true and false as truth-values while in a many-valued logic we have more than two truth-values (they can be three, four or even infinite). The advantages that many-valued logics have on classical logic is that they’re better at formalizing things like the human behavior. We can now easily see that MAL is based on a many-valued logic with 10 different truth-values and so that the CL user above would have no problem building his list:

  1. Likes Keroro ⇒ 10
  2. Likes Selector Spread Wixoss less than Keroro⇒ 1≤n≤9
  3. Dislikes Sword Art Online ⇒ 0

 Now it’s easy to see that the same problem present in CL is still present in MAL; but it’s more unlikely to appear. Indeed let’s suppose that Selector Spred Wixoss got a 9 and that the user “likes Koe no Katachi more than Selector Spread Wixoss but less than Keroro2: this is the same problem as above, the user would like to put a vote between 9 and 10 but on MAL this isn’t possible. A solution could be to give up on MAL and move over to AL where we have votes ranging from 0 to 100; but, as you can guess, this wouldn’t make the problem disappear even if it make it less likely to happen.

The way to solve this problem once and for all is to find a logic where it’s always possible to find a truth-value between two given truth-values: such logic exists and it’s called fuzzy logic. In fuzzy logic truth-values are real numbers in the interval [0,1]; it’s then clear that it’s always possible to find a truth-value between other two since the line of real numbers is a linear continuum and so it’s possible to perfectly formalize every “I like A more than B and less than C” statements. Unfortunately such a logic system would potentially involve the concept of infinity that our computers can’t handle and so it’s only possible to have anime-list sites based on multi-valued logics: the more truth-values those logics have the more they’re good at formalizing human behavior when it comes to liking and disliking animes.

That does not mean that a site built on a truth-values logic is necessary better than AL and MAL: such an high number of possibilities will make the process of voting tedious and the act of scrolling lists to find a particular vote on a particular anime incredibly weird; even if more truth-values a logic have better it approach fuzzy logic and so it can formalize human behavior better we surely do not need a trillion truth-values to vote animes. That’s why I use AL and its 0 to 100 voting system: it’s better than MAL’s 0 to 10 voting system in precision while still easy and not tedious to use and read.


  1. Nothing personal Sword Art Online.
  2. Such a situation is likely to appear with a decent number of shows completed.

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