PLEXIL5 is a Formal Verification Environment for PLEXIL
The Plan Execution Interchange Language (PLEXIL) is an open source
synchronous language developed by NASA for commanding and monitoring
autonomous systems. PLEXIL Formal Interactive Verification Environment
(PLEXIL5) is a tool that implements a formal executable semantics of
PLEXIL. PLEXIL5 provides a graphical interface that enable access to
formal verification techniques such as model-checking, symbolic
execution, theorem proving, and static analysis of plans. The
graphical environment supports formula editing and visualization of
counterexamples, interactive simulation of plans at different
granularity levels, and random initialization of external environment
variables.
PLEXIL’s operational semantics has been formally specified and key
meta-theoretical properties of the language, such as determinism and
compositionality, have been
formally verified in the Prototype
Verification System (PVS). This formalization yields a formal
executable semantics of the language that serves as an efficient
formal interpreter and reference implementation of PLEXIL. This formal
semantics is at the core of the verification capabilities of
PLEXIL5. The formal analysis capabilities offered by PLEXIL5 are based
on PLEXIL’s rewriting logic semantics written in the Maude system and verified in
PVS.
The graphical user interface has been developed in Java using
the model-view-controller pattern. The object oriented model
represents the hierarchical structure of plans, their execution
behavior, and the external environment. The view consists of several
classes that present the user with views of the tree-like-structure of
plans. The controller consists of a custom controller-facade class and
listener classes using and extending the Java framework. PLEXIL5
supports a number of input formats defining plans. For this purpose,
the tool links a series of parsers and translators that internally
generate the format supported by the rewriting logic semantics of the
language implemented in Maude and
construct an object oriented plan model from Maude’s output.
Java and Maude communicate as processes at the operating system’s
level with help of the Java/Maude Integration API, developed as part
of the PLEXIL5 framework.
PLEXIL5 v0.0 (May-31-2018)
Maude Interpreter Binaries. Copy maude.linux64, maude.linux, maude.intelDarwin to plexilite folder.
In build directory:
$ ant run
The code in this repository is released under NASA’s Open Source
Agreement. See the directory LICENSES; see also the copyright notice at the end of this file.
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