In July, 2019 at the Second Symposium on Analytic Number Theory in Cetraro, Italy, Dimitris Koukoulopoulos and James Maynard announced the solution of the Duffin-Schaeffer Conjecture (see also this article ), a 78-year old problem in Diophantine approximation concerned with which real numbers \(\alpha \) have infinitely many rational approximations of the form \[ \Big| \alpha - \frac{a}{b} \Big| < \frac{f(b)}{b}, \quad \text{gcd}(a,b)=1 \tag{1} \] for an arbitrary non-negative function \( f(b) \). The crux of the proof is to show that whenever the function \( f \) satisfies \[ \sum_{b=1}^\infty \frac{f(q)\phi(q)}{q} = \infty, \] where \( \phi \) is Euler's totient function, then the set of \( \alpha \in [0,1] \) so that (1) has infinitely solutions has full Lebesgue measure 1 (that is, the exceptional set has measure zero).