If you find any great resources for understanding mathematical notation, place your findings here, or ask questions where you can’t find them.
I have always found this list to be extremely helpful. Taken from Mathematical Physics by Sadri Hssani
From the class chat:
In finite element literature we use the | | to represent a seminorm. There may be instances where we use notation a little different than you’ll find in other literature simply because we are working with far more abstract concepts. However it may help to realize that the length of a vector in \R^n is indeed a norm and therefore a seminorm so this notation is not a large deviation from what’s used in primitive linear algebra.