MathLabs

第4题

A magician has one hundred cards 数ed 11 到 100100. He puts them in到three boxes, red, white 且blue, 每个nonempty. A member selects two boxes, chooses one card 从each, 且announces their 和. Given th是和, magician identifies box 从which no card was chosen. How many assignments 的cards 到three boxes make th是always possible?
第 2/5 步：使用 和set bound
上一步下一步
∣X+Y∣≥∣X∣+∣Y∣−1.|X+Y|\ge|X|+|Y|-1.
详细分析

应用 standard finite-set 和set inequality 到three boxes.