Hint: For any space $X$ and any $x\in X$, the set of functions vanishing at $x$ is a maximal ideal in $C(X)$.

Maximal ideals of commutative unital C* algebra using Gelfand-Naimark theorem
I have seen this question about updates of the D&amp;D 4th Edition books, and it got me thinking.
Since I got my Kindle I have not read a single paper novel; they have fewer drawbacks compared to digital copies than rpg rulebooks.


Dead-tree types have some benefits like looking good on a bookshelf, but any ebook reader weighs less with 100 novels than the usual hard-cover book. 
If you want to look for the damage of Ares Alpha, even with a half-decent tablet it takes less than 2 seconds.  
Digital copies do not get worn, they never get unwanted earmarks, but you can bookmark them.
Rulebooks do get updates, and unless you are willing to take a pen to your book, your hard copies will never contain them. The pdfs can be edited and resent to the buyers. 
Even better is the WotC approach with the DDI, you can look up any monster or item or (almost any) rule, in the most recent form, for 3 years at the cost of seven books. 


I think this is the way to go, even considering the horribly slow character builder. Although I must admit good illustration can help build the athmosphere.

So what am I missing? Why are people buying rpg rulebooks in paper format? Why are books even published, I do not need to know if feats are supposed to be on the right page and skills on the left, I just want a list of them, filterable any way I want. 

Is this just a necessary part of earning money? I understand that pdfs are copied illegally, but the Compendium is not. 
