I haven't read the patent, but I assume Keurig patents a way to improve cups in some obscure way that probably doesn't matter but for which they can claim nove

I haven't read the patent, but I assume Keurig patents a way to improve cups in some obscure way that probably doesn't matter but for which they can claim novelty. Their patent must explain how to implement this "improvement". Now, in order to be compatible with a Keurig machine, you must implement this "improvement", which is really the point of the "improvement" in the first place and why I keep putting it in quotes. But compatibility with a Keurig machine is not what's patented and there can be plenty of other undisclosed details that prevent someone from making Keurig compatible coffee cups.