Very engaging lecturer, great sense of humor. Extremely timely with email repsonses. Grading was homework, 2 midterms, and a final. Holds a lot of office hours. Homework can be tough but he'll help you in OH. Midterms generally easier than homework. Also just a nice guy

HW 25%, 2 midterms 15% each, 1 final 45%; He's very funny and genuinely helps so much in office hours. Favorite math class at UCSB thus far and only class I ever went to that I waNTed to go to because the course content is fun (he makes it fun). Homework was light (5ish problems per week) and if they're hard, mathlab helps so much.

Took this Spring 2022. Great prof! He won't surprise you on a test with anything you wouldn't be capable of doing, and he curves generously. HW is tough but going to office hours really helps clarify most of it. He responds to emails as well.

Casteels is an awesome professor. His lectures were always very clear and structured. His problem sets were extremely fun to complete; he never failed to provide interesting questions. The final included computing R(3,4), and he broke the proof into manageable parts. UCSB will miss him!

Amazing professor. I'm taking his Number System and Combinatorics this quarter. The workload is ~4 questions/week/course. One of the most memorable moments was when a HW problem in Combo was a trivial case of an open problem. I emailed him at midnight, said I proved a stronger result. He replied super fast with tons of books and related materials.

Five points might be the upper limit of rate my professor, but definitely not the upper limit of Karel.