There are great tools like leetcode, topcoder, etc. for keeping our algorithm skills sharp. Are there any similar tools/forums for math problems at the level of calculus, probability, linear algebra, etc.?
Suppose you implement an algorithm published in a research paper and use it in your startup. Is it necessary to somehow "cite" the paper? Is it as informal as dropping the author(s) an e-mail and saying, "Hey, cool algorithm. Just wanted to let you know I used it..." or is there some formal legal process?
I am interested in purchasing a domain name that is currently up for sale. The owner is asking for an offer price. What is a good way to determine the price to offer, and on what terms are domains typically sold?
