A safety system, which stops the motion of a boat or other craft when a person falls off the craft, is comprised of a wireless transmitter carried by the person, a receiver-controller, an actuator, and a spring loaded kill switch. Examples in accordance with the present invention contribute to systems and methods for solving optimization problems that include constraints in the form of arbitrarily complex logical relationships between binary variables. To facilitate repeated data requests, an individual Web server client requests that one or more communication channels be cached. Also, such sensors would not interfere with the existing seat designs, and would not be adversely affected by the equipment of the seat such as seat heaters. The driving wiring line is connected to a wiring line in a different layer so as to form a multilayer wiring line. An aberration amount calculator calculates amounts of aberrations corresponding to aberrations, respectively, in the charged-particle beam from the amounts of features \u03bc, \u03c3, and \u03c1.