- Spot - LRE

Re: [Spot] command-line option to negate input formula
by Victor Khomenko 24 Sep '19

24 Sep '19

> > Could you add a command-line option for ltl2tgba to invert the input > formula before computing the automaton? > > Done. > https://gitlab.lrde.epita.fr/spot/spot/commit/7f21d3ff29ad3a513f261025c5 > 75e4676a14cc50 Great - many thanks! > Any opinion on what passing --negate twice should do? A really good and nerdy one - twice the smiley face! :-) :-) Cheers, Victor.

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command-line option to negate input formula
by Victor Khomenko 24 Sep '19

24 Sep '19

Hi, Could you add a command-line option for ltl2tgba to invert the input formula before computing the automaton? Yes, it's trivial to do externally, but there are good reasons to have this option: * this would remove an extra step from model checking toolchains (where the automaton is built for the negation of a formula) * if the formula goes through a toolchain, it's better to keep equivalence all the way through to the automata, so that the user can easily see that the property has not been broken by transformations, and also comprehend any formula-related diagnostics logged by the tools. Thanks, Victor.

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LTLf formulas
by Yong Li (李勇) 10 Sep '19

10 Sep '19

Dear Spot developers, I am Yong Li from Chinese Academy of Sciences and I am writing to you to ask a question about parsing LTLf (LTL over finite traces) formulas. Spot supports LTL with finite semantics (LTLf) but I found out that Spot eagerly simplifies the input formulas with LTL semantics. For instance, if I use command line ltlfilt --from-ltlf -f "a U !(X True)", Spot immediately gives me 0. This is not correct since the input formula should be satisfiable in LTLf semantics. I wonder whether there is a way to get around it? Is there a an option I can use to make Spot parse the formula without simplying it? Regards, Yong

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Issue with SPOT and LTLf
by Andrew Wells 28 Aug '19

28 Aug '19

I'm trying to use SPOT to build an automaton for an LTLf formula, but I think there is a bug. I'm using this code (based on https://spot.lrde.epita.fr/tut12.html) #include <iostream> #include <spot/tl/ltlf.hh> #include <spot/tl/parse.hh> #include <spot/twaalgos/hoa.hh> #include <spot/twaalgos/remprop.hh> #include <spot/twaalgos/translate.hh> int main() { spot::parsed_formula pf = spot::parse_infix_psl("((a && b) U (! (X 1)))"); if (pf.format_errors(std::cerr)) return 1; spot::translator trans; trans.set_type(spot::postprocessor::BA); trans.set_pref(spot::postprocessor::Small); spot::twa_graph_ptr aut = trans.run(spot::from_ltlf(pf.f)); spot::remove_ap rem; rem.add_ap("alive"); aut = rem.strip(aut); spot::postprocessor post; post.set_type(spot::postprocessor::BA); post.set_pref(spot::postprocessor::Small); // or ::Deterministic aut = post.run(aut); print_hoa(std::cout, aut) << '\n'; return 0; } In LTL, this would be a contradiction, but in LTLf it is not as the next operator cannot be true at the last timestep. There seems to be an issue with SPOT where it simplifies the automaton as though the formula is in LTL, yielding an incorrect automaton. Am I using this correctly? I'd be willing to write a patch if this is indeed a bug. Thanks, Andrew Wells

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Change log from version 2.0 to 2.8
by M. H. Zibaeenejad 24 Aug '19

24 Aug '19

Hi, I have used the version 2.0 of your online tool for LTL to Buchi automata translation. At the time the tool did not return a deterministic Buchi automaton, but the new version does the transformation with ease. I was wondering if something fundamental has changed in your code that made this possible. Do you have the Changelog from 2.0 to 2.8? Here is the formula i used : G(!e) & G((c&!d&Fd)->(p Ud)) & G(a&!c->(!c W(b&!c))) & GF(a)&GF(b)&GF(c)&GF(d) RegardsHadi Zibaeenejad,PhDUniversity of Waterloo

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Compiling Spot on windows
by Maxime Bouton 04 Jul '19

04 Jul '19

Dear Spot maintainers, I was wondering if there had been some work on compiling Spot with the python bindings on windows? I have been able to create windows binaries for libspot.so using a cross-compilation environment and mingw with the option `--disable-python`, and I saw that there was a similar example in the continuous integration configuration on gitlab. However I would be interested in having the python bindings as well. * Do you think it is possible for one to get the python bindings for windows? * Do you have any hints on how one could proceed? In the cross-compilation environment I had an error in the `./configure` step, related to not being able to find `python.h` on the target (windows 64bits) and was not able to make much progress in that direction. Thanks for your help, Maxime

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Theorem question
by Scott M. Staley 30 Jun '19

30 Jun '19

Hi all, A quick (?) question. When I put the following LTL formula into SPOT online: G (G (p => Gp ) => Gp) => (FG p => Gp) SPOT says it is equivalent to 1. Therefore I assume it’s a theorem of LTL. My question: Is there anyway to see the series of rewrites of the formula to show how it gets form the original formula to “true”? Thanks, Scott

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Bug in ltlsynt - lar algorithm
by Guillermo Alberto Perez 18 Jun '19

18 Jun '19

Hello, While running tests for SYNTCOMP 2019 we found that ltlsynt outputs an incorrect controller on one of our benchmarks: simple_arbiter_enc_2.tlsf (available from https://bitbucket.org/swenjacobs/syntcomp/src/master/SelectedBenchmarks2018…) I am calling the tool with --aiger --algo=lar and using iimc as our model checker. Best, Guillermo

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LTLf to NBAs: inconsistent results from code and command line
by Yong Li (李勇) 04 Jun '19

04 Jun '19

Dear Spot developers, I am Yong Li, a Phd student from Chinese Academy of Sciences. I am writing to you to ask an implementation question about the translation from LTLf to NBAs in Spot. currently if I use following command line: ltlfilt --from-ltlf -f "((G((P83) -> (X((P145)) | X(X((P145))) | X(X(X((P145)))) ))) -> ( G((P21) -> (X( (P118) | (P83)) | X(X( (P118) | (P83))) | X(X(X((P118) | (P83)))) )) & G( (P118) -> X(!(P118))) & G( (P83) -> X(!(P118) U (P145)))))" | ltl2tgba | autfilt --remove-ap=alive --small -B I was able to get a weak DBA with only 8 states. However, if I use following c++ code to do the same job: auto pf1 = spot::parse_infix_psl(argv[1]); if (pf1.format_errors(std::cerr)) { std::cerr << "error: " << argv[1] << std::endl; return -1; } // formula auto f1 = pf1.f; std::cout << f1 << std::endl; // translate to ltlf //auto ltlf = spot::from_ltlf(f1, "alive"); spot::translator trans; trans.set_type(spot::postprocessor::BA); trans.set_pref(spot::postprocessor::Small); trans.set_level(spot::postprocessor::High); spot::twa_graph_ptr aut = trans.run(spot::from_ltlf(pf1.f)); spot::remove_ap rem; rem.add_ap("alive"); aut = rem.strip(aut); spot::postprocessor post; post.set_type(spot::postprocessor::BA); post.set_pref(spot::postprocessor::Small); // or ::Deterministic post.set_pref(spot::postprocessor::High); // or ::Deterministic aut = post.run(aut); I would get a DBA with 16 states, which has much more states than the one from the command line. The full source code is attached to this email. Could you tell me how I can change the code above so to get the same DBA from the command line? Thank you very much. BTW: I would like to appreciate the Spot tool which is a tool I would install on my every Ubuntu system. Yong

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Docker pull
by Jiraphapa Jiravaraphan 03 Jun '19

03 Jun '19

Dear Spot team, I've tried to pull docker image using command "sudo docker pull registry.lrde.epita.fr/spot-sandbox", however, I got the following response: "Unable to find image 'registry.lrde.epita.fr/spot-sandbox:latest' locally docker: Error response from daemon: error parsing HTTP 403 response body: invalid character '<' looking for beginning of value: "<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n<html><head>\n<title>403 Forbidden</title>\n</head><body>\n<h1>Forbidden</h1>\n<p>You don't have permission to access /v2/spot-sandbox/manifests/latest\non this server.<br />\n</p>\n</body></html>\n". See 'docker run --help'." , any insight would be appreciated. Best regards, Jiraphapa J.

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