TLA + "Specifying Systems" draft translation --Section 2.1 Behaviors ( "act")

This section points

• We will "act" ( $behavior$ ) is defined as the state series where the state variable is a set of operations for the assignment;
• Our system is defined as a set of "behavior" that may arise in the collection, each "act" have expressed a correct execution step system.

Before we try to define a system, let's look at how scientists are doing. For centuries, they have been using equations to describe the system, these equations to determine the state of the system is how to evolve over time, in which the state is composed by the value of the variable.

For example, the state of the Earth-Moon system by Earth and the Moon may be composed of four variables $e\_pos$、 $m\_pos$、 $e \ _vel$ and $m \ _vel$ values will be described, four values representing the position and velocity of the two objects, is the three-dimensional space element. Earth-Moon system represented by the equations, these equations the values of state variables represented as a time constant determined and certain functions, including the quality of these constants, an initial position and speed.

The behavior of the Earth-Moon system from a mapping function from time to state $F$ said, $F(t)$ a system in $t$ state time. Computer scientists study the traditional system of systems, we can pretend that it is a state change in discrete steps. Therefore, we will implement a systematic procedure to a sequence composed by the state. Formally, we will "act" ( $behavior$ ) is defined as the state series where the state is a set of operations for the variable assignment. Our system is defined as a set of "behavior" that may arise in the collection, each "act" have expressed a correct execution step system.