MathDB

The first quadrant of the Cartesian

0-x-y

plane can be considered to be divided into an infinite set of squares of unit side length, arranged in rows and columns , formed by the axes and lines

x = i

and

y = j

, where

i

and

j

are non-negative integers. Is it possible to write a natural number

(1,2, 3,...)

in each square , so that each row and column contains each natural number exactly once?
(V . S . Shevelev)

Problem Statement