To the Editor: One of the most important issues in robotics is environment-mapping. Nowadays, robotics is going to make robots think like humans. We proposed a novel model of environment-mapping for mobile robots that is based on hippocampal function. In the past three decades, several approaches have been introduced for environment-mapping. Chatila and Laumond in1 have introduced the metric map that is based only on environmental geometric information. Matari'c has proposed topologic map that is expressed as a graph, based on the relationship between different regions.2 Mozos et al.3 provided a conceptual map that enables robots to perceive the environment like humans. Mark C. Fuhs4 presented a map based on the neural network, which was inspired by hippocampus cells. Tokunaga and Furukawa in5 used vision to display maps in a two-level, self-organizing map. However, in the case of a high-resolution map, its complexity increases.