# German Retiree Solves One of the World’s Hardest Maths Equation

Without anyone knowing!

The Gaussian Correlation Inequality (GCI), a maths problem that even the most experienced mathematicians have struggled to solve has been solved by a retired German statistician in his bathroom.

Refusing to believe that the scientific society had been outsmarted by such an unlikely figure, the proof went widely unacknowledged.

"I know of people who worked on it for 40 years, I myself worked on it for 30 years."  Donald Richards, a statistician from Pennsylvania State University

First developed in the 1950s and properly refined in 1972 the CGI principle sounds fairly simple:

Two shapes overlap- say a rectangle and a circle, what is the probability of hitting both with a dart?

If you throw a bunch of darts at a target you’ll discover a bell curve- or what scientists call a ‘Gaussian distribution’. The majority of darts thrown at the board will land in the overlap. A specific majority-proportional to the number of darts outside the overlapped shapes.

The Gaussian correlation inequality explains that the odds of hitting the overlapped rectangle and circle are high or even higher than of it landing inside the rectangle multiplied by the likelihood of it landing inside the circle.

Being an arrogant young mathematician ... I was shocked that grown men who were putting themselves off as respectable math and science people didn't know the answer to this, said Loren Pitt from the University of Virginia.

"Fifty years or so later, I still didn't know the answer," Said Pitt

And now German statistician, Thomas Royen, has proved the equation while brushing his teeth. Royen wrote everything down in a word document and posted it on the internet as well as sending it to Penn State, where it was confirmed.

It was harder to convince the mathematical community.

"I am used to being frequently ignored by scientists from [top-tier] German universities. I am not so talented for 'networking' and many contacts. I do not need these things for the quality of my life." Said Wolchover.

Only in the last 12 months has the equation been accepted by the mathematical community.

A few more questions need to be fleshed out including why in the age of the internet this was missed.

"It was clearly a lack of communication in an age where it's very easy to communicate," said o Bo'az Klartag from the Weizmann Institute of Science and Tel Aviv University in Israel.

But anyway, at least we found it - [and] it's beautiful.