In
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to practical disciplines (includi ...
, an action language is a language for specifying
state transition system
In theoretical computer science, a transition system is a concept used in the study of computation. It is used to describe the potential behavior of discrete systems. It consists of states and transitions between states, which may be labeled with ...
s, and is commonly used to create
formal model
In logic, mathematics, computer science, and linguistics, a formal language consists of string (computer science), words whose symbol (formal), letters are taken from an alphabet (formal languages), alphabet and are well-formedness, well-formed ...
s of the effects of actions on the world. Action languages are commonly used in the
artificial intelligence
Artificial intelligence (AI) is intelligence—perceiving, synthesizing, and inferring information—demonstrated by machines, as opposed to intelligence displayed by animals and humans. Example tasks in which this is done include speech r ...
and
robotics
Robotics is an interdisciplinary branch of computer science and engineering. Robotics involves design, construction, operation, and use of robots. The goal of robotics is to design machines that can help and assist humans. Robotics integrate ...
domains, where they describe how actions affect the states of systems over time, and may be used for
automated planning
Automation describes a wide range of technologies that reduce human intervention in processes, namely by predetermining decision criteria, subprocess relationships, and related actions, as well as embodying those predeterminations in machines ...
.
Action languages fall into two classes:
action description languages and action query languages. Examples of the former include
STRIPS,
PDDL, Language A (a generalization of STRIPS; the propositional part of Pednault's
ADL), Language B (an extension of A adding ''indirect effects'', distinguishing static and dynamic laws) and Language C (which adds indirect effects also, and does not assume that every fluent is automatically "inertial"). There are also the Action Query Languages P, Q and R. Several different algorithms exist for converting action languages, and in particular, action language C, to
answer set programs.
Since modern answer-set solvers make use of
boolean SAT algorithms to very rapidly ascertain
satisfiability
In mathematical logic, a formula is ''satisfiable'' if it is true under some assignment of values to its variables. For example, the formula x+3=y is satisfiable because it is true when x=3 and y=6, while the formula x+1=x is not satisfiable over ...
, this implies that action languages can also enjoy the progress being made in the domain of boolean SAT solving.
Formal definition
All action languages supplement the definition of a
state transition system
In theoretical computer science, a transition system is a concept used in the study of computation. It is used to describe the potential behavior of discrete systems. It consists of states and transitions between states, which may be labeled with ...
with a set ''F'' of ''
fluents'', a set ''V'' of values that fluents may take, and a function mapping ''S'' × ''F'' to ''V'', where ''S'' is the set of states of a state transition system.
See also
*
Linear temporal logic
*
GOLOG
*
Fluent calculus The fluent calculus is a formalism for expressing dynamical domains in first-order logic. It is a variant of the situation calculus; the main difference is that situations are considered representations of states. A binary function symbol \circ is u ...
*
Situation calculus The situation calculus is a logic formalism designed for representing and reasoning about dynamical domains. It was first introduced by John McCarthy in 1963. The main version of the situational calculus that is presented in this article is based o ...
*
Event calculus The event calculus is a logical language for representing and reasoning about events and their effects first presented by Robert Kowalski and Marek Sergot in 1986. It was extended by Murray Shanahan and Rob Miller in the 1990s. Similar to other l ...
References
{{DEFAULTSORT:Action Language
Programming language classification
Automated planning and scheduling
Transition systems