Pythagoras is a multi-sided agent-based model (ABM) created to support the growth and refinement of the U.S. Marine Corps Warfighting Laboratory's's Project Albert. Anything with a behavior can be represented as an agent. The interaction of the agents and their behaviors can lead to unexpected or emerging group behaviors, which is the primary strength of this type of modeling approach. As Pythagoras has grown in capability, it has been applied to a wide variety of tactical, operational and campaign-level topics in conventional and irregular warfare. Capabilities Pythagoras offers a unique set of capabilities in the area of agent-based simulations: Incorporates soft rules to distinguish unique agents Uses desires to motivate agents into moving and shooting Includes the concept of affiliation (established by sidedness, or RGB color value to differentiate agents into members of a unit, friendly agents, neutrals, or enemies Allows for behavior-changing events and actions (called triggers) that may be invoked in response to simulation activities Retains traditional weapons, sensors, and terrain Example application Irregular Warfare Pythagoras is best employed to study situations that are not well represented in traditional, legacy simulations. An illustrative example is an Improvised explosive attack on a vehicle convoy. Figure 1 shows a convoy of blue vehicle agents traveling down a road in an urban setting. There are three improvised explosive device agents emplaced along the roadside, and a triggering agent alongside the building. The convoy agents are told to follow one another, except for the leader agent at the head of the column, whose behavior is to drive along the road. Figure 2 shows the situation after two of the vehicles have passed the corner of the building, 13 time steps after Figure 1. The triggering agent's behavior is to watch for blue vehicles. Upon seeing two vehicles, the triggering agent orders the IEDs to change their behavior from completely passive (do nothing) to aggressive (attack!). The IEDs explode, killing two convoy vehicles, which become transparent, and damaging two others, which change their color. The IEDs did not attack the convoy until ordered to do so by the triggering agent. This simple scenario was constructed by one analyst in about two hours, and illustrates both the ease of use and the applicability of Pythagoras to many combat and non-combat analysis situations. This scenario was used to examine alternatives for convoy protection, such as IED Background Agent-based simulations create software entities that are capable