During what was an unremarkable summertime ’s morning , a 67 - yr - older valet de chambre had a modern - day constantan   minute , allowing him to suddenly crack a chance job that   has mix up mathematical statistician   since the 1950s .

Quanta Magazinerecently reported the story ofan unassuming sack out German mathematical statistician call Thomas Royen , who came up with a   mathematical validation for   the Gaussian correlation inequality ( GCI ) during   a brief flash of inspiration while brush his tooth in July 2014 .

The GCI principle is all about geometry and probability . It was first suggest in the 1950s and more eloquently formulated in 1972 . Although unco simple to understand , it has evade numerical explanation .

Here ’s an example of how it works : think you are throwing darts at a target made up of any two convex symmetrical shapes that are centre on the same point . More simply put , a target made up a rectangle with a round cold shoulder - out put down over the top of it . The phone number of flit that   bump off the circle , rectangle , or both will come out in a normal bell - curve distribution , known as a Gaussian emplacement , with the majority of the darts hitting in the overlapping section .

GCI articulate that the probability of a flit slay the convergence is always adequate to or high than the individual chance of it   landing inside the rectangle procreate by the private probability of landing in the roofy . This makes common sense , but it has proved to be a pain to explain mathematically .

“ I know of mass who exploit on it for 40 year , ” Donald Richards , a mathematical statistician at Pennsylvania State University , toldQuanta Magazine . “ I myself worked on it for 30 years . ”

Royen , however , found a remarkably satiny answer to it . The same solar day he had his eureka import , he typed up the calculations   on Microsoft Word ( as he   did n’t be intimate how to habituate the fancy Good Book central processor used by professional mathematicians ) and sent   the paperto the pre - print websitearXiv . The paper is called   “ A simple proof of the Gaussian correlation speculation . " He sent the solution   to a few statisticians   in the US who he cerebrate might be interested .

“ I got this clause by email from him , ” I. A. Richards lend . “ And when I reckon at it I knew instantly that it was solved . ”

His work has gone more or less unrecognized in   the field . However , that ’s for the most part due to Royen ’s relaxed mental attitude towards the whole result , choosing to avoid the foresightful and arduous match - review system of rules . With no career to judge and promote , he ’s just well-chosen that the proof is now ground .