- Spot - LRE

Spot tool
by רועי פוגלר 20 Oct '20

20 Oct '20

My name is Roi and I'm an Msc student at Bar Ilan University (Israel). I'm trying to use the spot tool (python version) and I'm trying to figure out how to build spot-automata (spot.twa_graph object) type when my input is the edges, states and accepting states. can you help me please with that? In addition, is there an example of Angluin implementation using Spot? Regards, Roi

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Spot tool
by רועי פוגלר 19 Oct '20

19 Oct '20

My name is Roi and I'm an Msc student at Bar Ilan University (Israel). I'm trying to use the spot tool (python version) and I'm trying to figure out how to build spot-automata (spot.twa_graph object) type when my input is the edges, states and accepting states. can you help me please with that? In addition, is there an example of Angluin implementation using Spot? Regards, Roi

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Re: [Spot] Explicit order of sub-formulas in formula constructor
by Alexandre Duret-Lutz 06 Oct '20

06 Oct '20

On Tue, Oct 6, 2020 at 5:09 PM Niklas Metzger <niklas.metzger(a)cispa.saarland> wrote: > > Hi Alexandre, > > thank you for your fast response! I’m a bit confused on the meaning of creation time: > > >>> import spot > >>> f = spot.formula("Fa") > >>> ff = spot.formula("Ga") > >>> spot.formula.Or([f, ff]) > spot.formula("Fa | Ga") > >>> f = spot.formula("Ga") > >>> ff = spot.formula("Fa") > >>> spot.formula.Or([f, ff]) > spot.formula("Fa | Ga") > >>> n = spot.formula("Ga") > >>> nn = spot.formula("Fa") > >>> spot.formula.Or([n, nn]) > spot.formula("Fa | Ga") > > Is there some internal representation that does not create new objects if seen before? Yes. You can also use print(f.id()) to display the "serial number" of formula f. That's an identifier incremented for each new formula (new in the sense "not seen before"). This value is used to sort formulas (e.g., order the operands), or as hash value. But it is not necessarily unique in the case that so many formulas are created that the counter loops. -- Alexandre Duret-Lutz

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Explicit order of sub-formulas in formula constructor
by Niklas Metzger 06 Oct '20

06 Oct '20

Hi! I’m currently using Spot to manipulate LTL formulas (using Python) and encountered the following behaviour: The result of "spot.formula.Or([x,y])” possibly changes the order of the subformulas, e.g. globally will appear in front of finally. Is there a way to build formulas that stick to the given order? Best and thanks in advance Niklas

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Question on LTL to buechi automata
by Zhen Dong 24 Sep '20

24 Sep '20

Dear Spot team, Thanks for developing the nice tool Spot. I am a researcher at National University of Singapore using Spot in my research. I have a question about translating LTL to buechi automata using spot. My LTL properties are constraints over input/output sequences of a program, e.g., output W, output P always responds to input B (false R (! iB | (true U (oW & X (true U oP))))) where iB indicates that input B and oP indicates output P. The buechi automata of the negation of above formula given by Spot is in the following: [image: image.png] Here is a input/output trace to be evaluated: iH oZ iH oR iC oR iH oX iC oR iH oX iD oZ iJ oT iD oT iF oR iH oP iH oR iH oP iH oR iH oP iH oR iH oP iH oR iH oP iH oR iH oP iH oR iH oP iH *What I do not understand is that the proposition on the transition from state 0 to state 2 is iB & oW. How can I interpret it?* Given the input/output trace, there is no element that is iB and at the same time is oW. I assume the verification feeds element in the trace to the automata one by one. Do I miss something e.g., wrong configuration on the translation or some basic knowledge about verification? Can you give me some advice on this issue? Thank you very much. Best regards Zhen -- Zhen Dong Senior Research Fellow National University of Singapore https://www.comp.nus.edu.sg/~dongz/

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Spot Polish Notation Parsing
by Niklas Metzger 31 Jul '20

31 Jul '20

Hi Spot Team! First of all, thanks for providing and maintaining such a great tool! I stumbled over a problem with formulas in polish notation: Parsing a formula like “-> a b” returns the “syntax error, unexpected implication operator” (Also tested on the website). It seems like implication and equivalence are not supported by that parser. Is there a technical reason for that and if not, could you give me a hint how to implement it? Thanks in advance Niklas Metzger

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Segfault when postprocessing large automaton
by Reed Oei 20 Apr '20

20 Apr '20

Hello, I am encountering a bug where Spot segfaults when I try to postprocess a relatively large automaton. I have uploaded the file to http://reedoei.com/files/smaller-inner.aut.zip; it has 113930 states and 1537155 edges. I tried to come up with a smaller example but was having trouble doing so. Below is the sequence of commands, using the Python bindings, to reproduce this bug for me: import spot A = spot.automaton('smaller-inner.aut') B = A.postprocess('BA', 'Deterministic', 'Low') # Crashes here B.save('postprocessed.aut') I also tried using various other others for postprocess such as Small and Low, or Any and High (because Any and Low/Medium does nothing). I am using Ubuntu 18.04, Python 3.6.9, and Spot 2.8.7 (but also tried with 2.8.6). Thank you, Reed Oei

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accepting_run() returning words containing false
by Jens Kreber 10 Apr '20

10 Apr '20

Hello, I am using spot to check randomly generated LTL formulas for satisfiability and extract traces / words fulfilling the formula if satisfiable. I have come across behavior which I do not understand and am therefore asking on this list about it. I would be very happy if you could help me with the issue. I'm using the python interface and call some_formula.translate().accepting_run() which usually either returns None if unsatisfiable or a valid trace, which I then convert using spot.twa_word() and inspect afterwards. Most of the time, this works as expected, but I've experienced several cases now where the produced trace contains a False (0) literal. Here, two cases must be distinguished: 1. The formula is satisfiable There exist formulas like "!b & e U (a & b & c)" which are quite obviously satisfiable, but still accepting_run() returns a trace with 0 in it, although there are other valid traces without False in them. 2. The formula is unsatisfiable There also exist formulas like "X!c & X(b & c & d & a U e)" which are unsatisfiable, and accepting_run() returns a trace with 0 in it. Normally, for unsatisfiable formulas (like "a & !a") it just returns None. I'd find point 2 alone totally okay, but I think point 1 is actually problematic since the trace I'm looking for exists, but isn't returned. So my question is whether I'm using spot incorrectly somehow or if this is actually a bug. I also attached a small list of formulas and traces with the described behavior. BTW I'm on Linux, Ubuntu 16.04, using spot 2.8.7 compiled from the tar.gz. I'm looking forward to your responses! Regards, Jens Kreber

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Re: [Spot] Site is not responding
by Alexandre Duret-Lutz 27 Feb '20

27 Feb '20

On Thu, Feb 27, 2020 at 10:33 AM Ranjana N <ranjana.nallamalli(a)gmail.com> wrote: > > The following website: > > spot.lrde.epita.fr Thanks. Our sysadmin said he banned all non-french IPs two days ago because of a DDOS attack that would fill the ram of our shared web server in just 1sec. Unfortunately he had no time yesterday to work on this. He tried to lift the ban a few minutes ago, and the server went down in a couple of seconds again. He is currently trying to look for a smaller range of IPs to block. -- Alexandre Duret-Lutz

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Disable doc generation
by Jaime Arias 27 Feb '20

27 Feb '20

Dear all, I was wondering if there exists an option to disable the generation of the documentation. Thank you in advance, Best, Jaime -- -------------------------------------------------------------- Jaime Arias https://lipn.univ-paris13.fr/~arias CNRS Research Engineer (LoVe Team) LIPN, CNRS UMR 7030 Institut Galilée - Université Paris 13 99 Avenue Jean-Baptiste Clément, F-93430 Villetaneuse, France tel:[+33] 01 49 40 40 67 --------------------------------------------------------------

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