Чувство юмора у математиков

https://www.facebook.com/photo.php?fbid=868093980553&set=a.515700005903.2094293.1246113&type=1&theater¬if_t=photo_reply

https://avva.livejournal.com/3362088.html

Для незарегенных в ФБ копирую текст Риббета:
"I took at graduate algebra course at Brown when I was an undergraduate. I bought a copy of Lang's "Algebra," 3rd edition around that time. It was the bible of graduate algebra, and I suppose that it still is. When I was at Harvard, I studied very hard for the written qualifying exam that we sat for at the end of our first year of graduate work. I spent months mastering the core material in algebra, topology and analysis. I got a little frustrated by Lang's style and wrote the comment that you see in black ink. Years later, Serge had my office in Princeton while I was away in Paris. As usual, he consulted his own books, and he found my comment. He added his own (bottom of the page) and told me about it when I returned to the US. We both had a good laugh."