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In computer programming, a guard is a Boolean expression that must evaluate to true if the execution of the program is to continue in the branch in question. Regardless of which programming language is used, a guard clause, guard code, or guard statement is a check of integrity preconditions used to avoid errors during execution.
Figure 2: Extended state machine of "cheap keyboard" with extended state variable key_count and various guard conditions. The state diagram from Figure 2 is an example of an extended state machine, in which the complete condition of the system (called the extended state) is the combination of a qualitative aspect—the state variable—and the ...
Activity diagrams [1] are graphical representations of workflows of stepwise activities and actions [2] with support for choice, iteration, and concurrency. In the Unified Modeling Language, activity diagrams are intended to model both computational and organizational processes (i.e., workflows), as well as the data flows intersecting with the related activities.
An activity diagram, with the activity "Cooking Spaghetti" outlined with an "Activity frame" An activity in Unified Modeling Language (UML) is a major task that must take place in order to fulfill an operation contract. The Student Guide to Object-Oriented Development defines an activity as a "sequence of activities that make up a process."
Similarly, in UML, a standard concept-modeling notation used in software development, the activity diagram, which is a type of flowchart, is just one of many different diagram types. Nassi-Shneiderman diagrams and Drakon-charts are an alternative notation for process flow.
Banker's algorithm is a resource allocation and deadlock avoidance algorithm developed by Edsger Dijkstra that tests for safety by simulating the allocation of predetermined maximum possible amounts of all resources, and then makes an "s-state" check to test for possible deadlock conditions for all other pending activities, before deciding whether allocation should be allowed to continue.
A guarded command consists of a boolean condition or guard, and a statement "guarded" by it. The statement is only executed if the guard is true, so when reasoning about the statement, the condition can be assumed true. This makes it easier to prove the program meets a specification.
A directed graph. A classic form of state diagram for a finite automaton (FA) is a directed graph with the following elements (Q, Σ, Z, δ, q 0, F): [2] [3]. Vertices Q: a finite set of states, normally represented by circles and labeled with unique designator symbols or words written inside them