MathDB
Minimum of Floor Functions

Source: Benelux MO 2014 Problem 1

July 17, 2014
functionfloor functionalgebra unsolvedalgebra

Problem Statement

Find the smallest possible value of the expression a+b+cd+b+c+da+c+d+ab+d+a+bc\left\lfloor\frac{a+b+c}{d}\right\rfloor+\left\lfloor\frac{b+c+d}{a}\right\rfloor+\left\lfloor\frac{c+d+a}{b}\right\rfloor+\left\lfloor\frac{d+a+b}{c}\right\rfloor in which a, b, ca,~ b,~ c, and dd vary over the set of positive integers.
(Here x\lfloor x\rfloor denotes the biggest integer which is smaller than or equal to xx.)