One idle evening last October, Mehtaab Sawhney took up an old pastime. He began perusing the website erdosproblems.com, an updated record of the 1,179 conjectures left behind by the eccentric and ...

Released into the wild decades ago, Florida’s giant pythons have multiplied into an unstoppable force, devouring native wildlife and collapsing fragile ecosystems. Trump moves to undo tax rule that ...