Hi Alexandre, thank you very much for your comments. I also received the suggestion to use aliases to avoid the long [0 & !1 & !2 & !3 & ...] expressions in the body of the file. Now, the output of our library looks like in the attachment. According to ltl2tgba the output is correct (... for the automata/words that I checked). Best, Matthias On Tuesday, September 29, 2015 18:00:57 Alexandre Duret-Lutz wrote:

On Tue, Sep 29, 2015 at 5:09 PM, Matthias Heizmann

<heizmann@informatik.uni-freiburg.de> wrote:

...

Hi Spot developers,

I just extended our automata library https://ultimate.informatik.uni-freiburg.de/?ui=int&tool=automata_script_i nterpreter&task=automataScript&sample=1954831617 with support to write Büchi automata in the HOA format.

Sweet!

...

Now, I just wanted to check a few results without implementing support to read HOA files. Syntactically my files seem to be correct, (example attached, file is read by Spot), but I also wanted to do some semantic check, e.g., test if a certain word is accepted.

From a semantic point of view, I suspect that you may have a problem because the HOA format assumes that the alphabet is 2^AP (i.e., each letter is an assignment of all atomic propositions), not AP. So the automaton you attached also accepts an infinite word where each letter is a&b, which somehow contradicts the name of the file.

...

Spot provides quite a number of sophisticated operations but I did not find something "simple" like an acceptance check. Have I overlooked it or is it not documented? For my purpose it is sufficient if it works on the "usual" Büchi automata.

You did not overlook anything: Spot does not export such a feature. I'll add that to the todo list.

Currently, you can still check acceptance of a word by representing this word as an automaton, and testing the interstection of the two automata using autfilt's --intersect option.

If you can write your word as an LTL or PSL formula, is it even easier than writing an automaton. E.g. testing the word a&!b ; b&!a ; followed by a cycle of just a&b

% ltl2tgba -f "(a & !b) & X(b & !a) & XXG(a & b)" -H | autfilt -q --intersect FinitelyManyAWithSink.hoa - && echo accepted || echo non-accepted accepted

I guess you could restrict the FinitelyManyAWithSink.hoa to disallow a and b to be accepted at the same time. autfilt --exclusive-ap can be handy for that:

% autfilt --exclusive-ap=a,b FinitelyManyAWithSink.hoa -H > F2.hoa

Now you can evaluate words (via LTL) as if the alphabet was AP:

% ltl2tgba -f "a & X(b) & XXG(b)" -H | autfilt -q --intersect F2.hoa - && echo accepted || echo non-accepted accepted

% ltl2tgba -f "a & X(b) & XXG(a)" -H | autfilt -q --intersect F2.hoa - && echo accepted || echo non-accepted non-accepted

(Note that --intersect is a filter. Without the -q option it returns the automata that interesect the reference automaton. If you want to compute the product of two automata to check the intersection by yourself, use --product instead.)

HTH