> As I said the legality of this is not so simple to answer … but once you bring IP into this it becomes a lot more complicated, calculus is also about ideas,

From a legal perspective, there is no such thing as “IP”. There are copyrights, patents, trademarks, and trade secrets. If you want to talk about legalities, you have to start by saying which of those four were violated. “Ideas” alone have no legal protections.