I'm not sure if "fundamental" makes much sense in relation to Lie groups. There are a lot of sets out there. Some of them are groups, others are topologies. Som

I'm not sure if "fundamental" makes much sense in relation to Lie groups. There are a lot of sets out there. Some of them are groups, others are topologies. Some are both. Similarly, there are people who have drivers licenses, and there are people who have blue eyes. Then there are people who have both blue eyes and drivers licenses. Those people are like lie groups.