Here are many of the terms used in our papers with detailed explanations

A - C - D - F - G - I - L - O - R - S


A message sent by the intersection manager to driver agents to acknowledge the receipt of a Cancel or Reservation-Completed message. Once a driver agent has received this message after sending a Cancel message, it knows that the reservation it held previously has been cancelled and it is free to send a new Request message.
A light model in which all the lights for all lanes in each direction are synchronized. If there are four directions of traffic - north, east, south, west - then the light model would dictate that all northbound lanes be given a green light simultaneously, followed by all eastbound lanes, southbound lanes, westbound lanes, and then northbound lanes and so forth. This light model is a good fit for scenarios involving many human drivers because green lights are frequent and it behaves very similarly to modern-day traffic lights.
Autonomous Vehicle
A vehicle which does not require a human driver. Autonomous vehicles are controlled by driver agents.


A message sent by driver agents to intersection managers indicating that the driver agent would like to cancel the reservation it is currently holding.
A message sent by driver agents to intersection managers indicating that the driver agent would like to change the parameters of the reservation it is currently holding.
A message sent by intersection managers to driver agents confirming a reservation. This can be in response to either a Request message or a Change-Request message. In the latter case, it indicates that the new reservation parameters are acceptable and the old reservation has been canceled.


Driver Agent
A computer program responsible for driving an autonomous vehicle. The driver agent is one of two classes of autonomous agents that make up the reservation system.
The difference between the amount of time it takes a vehicle to reach its destination and the time it would take to reach the destination under optimal conditions.
A message sent by driver agents to intersection managers indicating that the vehicle controlled by the driver agent has safely completed its journey across the intersection. This message can also be used to report useful statistics back to the intersection manager. This message was previously named Reservation-Completed, but was renamed for simplicity and brevity.


The "First Come, First Served" intersection control policy. This policy divides the intersection into an grid of tiles. To determine if reservation requests can be granted, the policy simulates the trajectory of the vehicle through the intersection. If, at every time step of the simulation, the simulated vehicle does not occupy any previously reserved tiles, the reservation is granted. Otherwise, it is rejected. This policy incurs the lowest delays to vehicles, but requires that all vehicles be autonomous and able to interact with the reservation system.
A version of the FCFS policy which gives preference to emergency vehicles. Once a Request or Change-Request message from an emergency vehicle is received, FCFS-Emerg rejects all reservation requests from lanes that do not contain emergency vehicles. The policy returns to the default FCFS behavior when all emergency vehicles successfully cross the intersection.
A version of the FCFS policy that can be used by human drivers. Associated with each instance of the policy is a light model. When FCFS-Light receives requests, it first determines if the lane in which the requesting driver agent is in will have a green light at the requested arrival time. If so, the reservation is confirmed. If the light will be yellow, the reservation is rejected. If the light will be red, the reservation parameters are passed to the FCFS portion of the policy which checks its database of reserved tiles as well as the off-limits tiles to determine whether or confirm or reject the reservation.


For the FCFS policies, the number of tiles on a side of the square grid in which the intersection is divided. Thus, if the policy divides the intersection into 24 × 24 = 576 tiles, the granularity of the policy would be 24.


Intersection Control Policy
The part of an intersection manager agent that determines whether or not to grant reservation requests. Some examples are FCFS, Stop-Sign, and Traffic-Light.
Intersection Manager
An agent that coordinates autonomous vehicles at an intersection. An intersection manager may also control the traffic lights at an intersection, in order to communicate with humans. Intersection managers receive reservation request messages (along with other types of messages) from driver agents and, using an intersection control policy, decide whether or not to grant these requests. The intersection manager is one of two classes of autonomous agents that make up the reservation system.


Light Model
A component of the FCFS-Light intersection control policy. The light model serves two purposes. First, it physically controls the traffic lights at the intersection. Second, it provides information to the intersection control policy about the state of the lights at any time. The policy may then use this information to make decisions regarding reservation requests.


Off-Limits Tiles
For the FCFS-Light policy, the tiles that are reserved for vehicles operating under the control of the light model. For example, if the light for the northbound left turn lane is green, then all tiles that could be used by a vehicle turning left from that lane are off-limits.
An intersection control policy used to represent optimal intersection control. This policy would never be used because it makes no safety guarantees. However, in simulation it performs well as a benchmark policy.


A message sent by intersection managers to driver agents indicating that the reservation request in a Request or Change-Request message was not acceptable. The message also may include a reason for why the request could not be granted.
A message sent by driver agents to intersection managers requesting a reservation. The message contains the parameters the intersection manager would need in order to determine if the reservation can safely be granted.
A set of parameters describing a vehicle's trajectory through an intersection.
See Done
Reservation System
A multiagent system composed of two different classes of agents: driver agents and intersection managers. The driver agents "call ahead" to the intersection manager in an attempt to resreve space-time in the intersection. The intersection managers are responsible for confirming or rejecting these requests in a manner that prevents vehicles from colliding in the intersection.


The custom time-based program we have written in order to run experiments on the reservation system. The program is written in Java.
A light model in which green lights are given to only one lane at a time. For example, the left turn lane of the northbound traffic would have a green light, while all other lanes would have a red light. Next, the straight lane of the northbound traffic would have a green light, then the right turn. Next, the green light would go through each lane of eastbound traffic, and so forth.
Spawn probability
The probability that at any time step of simulation the simulator will create ("spawn") a new vehicle driving towards the intersection. Even when this happens, a spawn may be aborted if there is no safe place to create the vehicle. This probability is used to control the amount of traffic in an experiment.
An intersection control policy that approximates a modern day stop sign. The policy rejects all requests that specify an arrival time that is not the current time. If the arrival time in the request is the current time, the behavior defaults to the FCFS policy. Because it can more precisely determine if vehicles are safe to proceed, it performs better than an actual stop sign with human drivers would. However, the policy could conceivably be used if there were a reason to bring all traffic to a stop before crossing the intersection (e.g. road construction or a downed power line).


A representation of a portion of the intersection used by FCFS policies. The policies record reservation information for each tile and then use that information to decide whether or not to grant future requests by vehicles.
An intersection control policy that emulates a modern-day traffic light. By granting reservations only when the corresponding lights would be green, vehicles are controlled in a manner identical to traffic lights.

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