https://github.com/caballa/covenant
A Tool for Intersecting Context-Free Grammars
https://github.com/caballa/covenant
concurrent-verification context-free-grammar intersection regular-languages
Last synced: 6 months ago
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A Tool for Intersecting Context-Free Grammars
- Host: GitHub
- URL: https://github.com/caballa/covenant
- Owner: caballa
- License: mit
- Created: 2015-03-13T18:33:30.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2017-12-19T06:01:15.000Z (almost 8 years ago)
- Last Synced: 2023-02-28T18:15:19.154Z (over 2 years ago)
- Topics: concurrent-verification, context-free-grammar, intersection, regular-languages
- Language: C++
- Homepage:
- Size: 622 KB
- Stars: 7
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Covenant #
Intersection of Context-Free Languages
## About ##
Covenant is a tool for testing emptiness of a set of context free
languages (CFLs). Since this problem is undecidable, Covenant
implements a CEGAR-based schema which might not terminate. Covenant
implements several refinement techniques. One of these refinements is
complete if the CFLs are regularly separable.
Read this [technical report](http://arxiv.org/abs/1411.5131) for details.
## Prerequisites ##
- Boost is required. It is recommended version 1.55 or newer
- Be sure to install the Boost program_options library and set `BOOST_ROOT`
## Installation ##
- `mkdir build && cd build`
- `cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=my_install_dir ..`
- `cmake --build . --target install`
The code has been tested only for X86_64 with clang++ 3.2 and g++ 4.8
## Usage ##
`my_install_dir/bin/covenant --help`
We describe the format of the CFLs through an example:
; this is a comment
( S1 -> [ A B];
A -> [ "a" "b"];
A -> [ "b" "b"];
A -> [ "a" S1 "a", "b" S1 "b" ];
B -> [ "a" "b" B];
B -> [ "a" "b"]
)
( S2 -> [ A B];
A -> [ "a" "a"];
A -> [ "b" "b"];
A -> [ "a" S2 "a", "b" S2 "b" ];
B -> [ "b" "a" B];
B -> [ "b" "a"]
)
The non-terminal symbol appearing on the left-hand side in the first
grammar production is considered the start symbol of the grammar. In
the above example the start symbols are `S1` and `S2`, respectively.
Terminal symbols must be between double quotes (i.e.,
`""`). Any symbol that is not between double quotes will be
interpreted as a non-terminal symbol.
Each grammar production is of the form `A -> [ ... ];` where `A` is a nonterminal
and `...` is a sequence of any nonterminal or terminal symbol separated by one or
more blanks. We also allow `A -> [ ... , ... ];` to express two grammar
productions with the same left-hand side A. That is, `A -> [ "a" S2 "a", "b" S2 "b" ];`
is syntactic sugar for `A -> [ "a" S2 "a"]; A ->[ "b" S2 "b" ];`
Note that all the right-hand side of the productions must ends up with the symbol `;`
except the last one.
If we wrap the above example into a file test.cfg and try
`covenant test.cfg`, you should obtain:
`Finished after 5 cegar iterations.`
` UNSAT`
Since covenant might not terminate, we provide a script `covenant-par`
that runs in parallel several configurations (i.e., heuristics) and
stops as soon as one of the them terminates:
`my_install_dir/bin/covenant-par file`
## Publications ##
- "A Tool for Intersecting Context-Free Grammars and Its Applications". G.Gange , J.A.Navas, P.Schachte, H.Sondergaard, and P.J. Stuckey. [(PDF)](http://www.clip.dia.fi.upm.es/~jorge/docs/cfg_nfm15.pdf) . NFM'15
- "A Complete Refinement Procedure for Regular Separability of Context-Free Languages". G.Gange , J.A.Navas, P.Schachte, H.Sondergaard, and P.J. Stuckey. [(PDF)](http://www.clip.dia.fi.upm.es/~jorge/docs/CFG-TCS-2016.pdf). TCS, 2016.