MathDB
Romanian Masters in mathematics 2010 Day 2 Problem 1

Source:

April 25, 2010
algebrapolynomialfunctionceiling functioninequalitiesalgebra proposed

Problem Statement

Determine whether there exists a polynomial f(x1,x2)f(x_1, x_2) with two variables, with integer coefficients, and two points A=(a1,a2)A=(a_1, a_2) and B=(b1,b2)B=(b_1, b_2) in the plane, satisfying the following conditions:
(i) AA is an integer point (i.e a1a_1 and a2a_2 are integers);
(ii) a1b1+a2b2=2010|a_1-b_1|+|a_2-b_2|=2010;
(iii) f(n1,n2)>f(a1,a2)f(n_1, n_2)>f(a_1, a_2) for all integer points (n1,n2)(n_1, n_2) in the plane other than AA;
(iv) f(x1,x2)>f(b1,b2)f(x_1, x_2)>f(b_1, b_2) for all integer points (x1,x2)(x_1, x_2) in the plane other than BB.
Massimo Gobbino, Italy