миленький задачник

по геометрии: euclidea.xyz/ru/ 

A book cover a day. #32

Handbook of Mathematical Logic.

This is vol 1, there are four of them. This part is dedicated to Model Theory. Which is still a mystery for most even mathematicians. Ok, Model Theory got a name since then, it's now Lawvere Model Theory.

а вот и стена, что я построил тут во время карантина

враг не пройдет