Answer: A heuristic
Explanation: A heuristic is a mental shortcut applied to solving problems. By using a heuristic here, Ivan may be able to reduce the time to find the map if he is correct. Heuristics serve as an efficient way to find solutions when we have limited time or knowledge.
While rational problem solving techniques are ideal, the resources we have at our disposal, especially time and limited intelligence do not always allow us to be rational at all times. This is why we use heuristics which is often a method of trial and error.