Here's a breakdown of the differences between each PDF style:
| Style | Class | Font | Theorem Environments |
|---|---|---|---|
| Style 1 | book |
Alegreya Sans | tcbthm |
| Style 2 | book |
Alegreya Sans | amsthm |
| Style 3 | book |
Arno* | amsthm |
| Style 4 | book |
Computer Modern | amsthm |
*To be replaced with Linus Romer's Elemaints when it is released.
Despite there not being a formal or precise definition of a forgetful functor, the term is often very useful in practice, similarly to the word “canonical”. The idea is that a “forgetful functor” is a functor that forgets structure or properties, and is best explained through examples, such as the ones below (see Example 9.5.3.1.3 and Example 9.5.3.1.4).
