Let be the set of ordered triples , where are integers with . Players and play the following guessing game. Player chooses a triple in , and Player has to discover 's triple in as few moves as possible. A move consists of the following: gives a triple in , and replies by giving the number . Find the minimum number of moves that needs to be sure of determining 's triple.
Solution
To solve this problem, we need to determine the minimum number of moves Player needs to make to uniquely identify the triple chosen by Player . The interaction between the players involves Player proposing a triple and Player responding with the distance formula given by:
The strategy is to choose queries that reduce potential candidates for while eliminating ambiguity between solutions. Let us detail the moves:
### Move 1: Initial Query
Choose .
The response simplifies to:
This response supports gathering information about the sum of pairs of the components of the true triple .
### Move 2: Distinguishing Pairs
For the second move, choose a query that isolates one component more directly. Consider .
The response is:
The change from the first to the second response helps compare differences and deduce possible values related to specific variables within .
### Move 3: Final Clarification
Choose .
The response is:
With these three strategic moves, it is ensured that the changes in response precisely pin down each possible combination of , differentiating them effectively.
### Conclusion
Given the information from the three queries and their responses, Player can uniquely determine Player 's triple . Therefore, the minimum number of moves required for Player to be sure of determining 's triple is: