tldr: Problem: agents should have a guess of where unseen enemies are.<br> 3 Approaches:

1. Occupancy Maps. Simplest method. When the enemy slips out of view, you are 100% sure of his location. A second later you are about 98% sure, but he could also be in surround areas. After a little while you're like 10% sure that he's in any given location.
2. Particle Filters. Since occupancy maps can be computationally expensive, you only keep track of the most likely places.
3. Simulacra. Calculate an actual simulated agent that acts like a real agent (to the best of your knowledge), just don't render them. This will probably get you the best, most accurate results.

Explicit simulcrum solves the problem that the previous two techniques shared: that agents aren't equally likely to walk in every direction.

Good quiz question