There are two StackExchange sites I regularly visit: MathOverflow and Mathematics. Roughly, the former is for research level questions and the latter is for almost any kind of mathematics question. Mathematics is very popular at 216 questions per day at this time of posting (I don’t know how this average is calculated). Unfortunately, that means most of the questions aren’t interesting to any given user. To help find the questions I might like, I used to use the ‘Favourite Tags’ and ‘Ignored Tags’ features, with ‘Ignored Tags’ set to not display. Unfortunately, this only works so well, since there are so many tags, and my ‘Ignored Tags’ list got very long:

calculus homework integration complex-numbers summation combinatorics statistics real-analysis notation education graph-theory matrices limits probability probability-theory induction differential-equations stochastic-processes differential-geometry logic inequality general-topology trigonometry svd pde computational-mathematics vector-spaces numerical-methods algebra-precalculus terminology arithmetic algorithms functions probability-distributions polynomials linear-algebra analytic-geometry logarithms sequences-and-series multivariable-calculus gradient-flows geometry game-theory elementary-number-theory functional-analysis systems-of-equations fourier-analysis optimization discrete-mathematics analysis finance matlab uniform continuity statistical-mechanics elementary-set-theory differential-topology limits-without-lhospital number-theory uniform-continuity group-theory trees metric-spaces absolute-value definition galois-theory rotations complex-geometry puzzle complex-analysis

To be clear, I like many of these topics, but most of the questions with these tags on math.stackexchange are not very interesting. However, I recently discovered the feature ‘Advanced Tag Subscriptions’ that can be accessed by clicking edit>advanced tag subscriptions on the right-hand side of any StackExchange site. There you can create various filters (think of them as custom StackExchange sites) that have options like this:

The effect is that you can make a whitelist, showing only the tags you like. Moreover these tags can be from different sites so your filter can display a questions listing from as many sites as you like. Unfortunately, there are still a few problems with this approach:

- You can only add tags and not more advanced filtering (like answers:0, score:3, etc.)
- You cannot search through the filtered questions, which would ameliorate the first point
- The page displaying the filtered questions does not display the score of the question, only the number of answers