d1ad744887
* doc/org/ioltl.org: Mention ltl2dstar and the changes to the prefix parser. * doc/org/ltlcross.org: Mention bench/ltl2tgba/sum.py. * doc/org/tools.org: Bump version number.
17 KiB
ltlcross
- Formula selection
- Configuring translators
- Getting statistics
- Detecting problems
- Miscellaneous options
#+EMAIL spot@lrde.epita.fr
ltlcross is a tool for cross-comparing the output of LTL-to-Büchi
translators. It is actually a Spot-based clone of LBTT, the
LTL-to-Büchi Translator Testbench, that essentially performs the
same sanity checks.
The main motivations for rewriting this tool were:
- support for PSL formulas in addition to LTL
- more statistics (like counting the number of logical transitions represented by each physical edge), output in a format that can be more easily be post-processed,
- more precise time measurement (LBTT was only precise to 1/100 of a second, reporting most times as "0.00s").
Although ltlcross performs the same sanity checks as LBTT, it does
not implement any of the interactive features of LBTT. Essentially
ltlcross will report problems, but you will be on your own to
investigate and fix them.
The core of ltlcross is a loop that does the following steps:
- Input a formula
- Translate the formula and its negation using each configured translator.
If there are 3 translators, the positive and negative translations
will be denoted
P0,N0,P1,N1,P2,N2. - Build the products of these automata with a random state-space (the same state-space for all translations).
- Perform sanity checks between all these automata to detect any problem.
- Gather statistics if requested.
Formula selection
Formulas to translate should be specified using the common input options.
Standard input is read if no -f or -F option is given.
Configuring translators
Each translator should be specified as a string that use some of the following character sequences:
%f,%s,%l,%w the formula as a (quoted) string in Spot, Spin,
LBT, or Wring's syntax
%F,%S,%L,%W the formula as a file in Spot, Spin, LBT, or
Wring's syntax
%N,%T the output automaton as a Never claim, or in
LBTT's format
For instance here is how we could cross-compare the never claims
output by spin and ltl2tgba for the formulas GFa and X(a U b).
ltlcross -f 'GFa' -f 'X(a U b)' 'ltl2tgba -s %s >%N' 'spin -f %s >%N'([](<>(a))) Running [P0]: ltl2tgba -s '([](<>(a)))' >'lck-o0-iDGV6y' Running [P1]: spin -f '([](<>(a)))' >'lck-o1-sA3FYp' Running [N0]: ltl2tgba -s '(!([](<>(a))))' >'lck-o0-1ClVQg' Running [N1]: spin -f '(!([](<>(a))))' >'lck-o1-wyErP7' Performing sanity checks and gathering statistics... (X((a) U (b))) Running [P0]: ltl2tgba -s '(X((a) U (b)))' >'lck-o0-ex1BYY' Running [P1]: spin -f '(X((a) U (b)))' >'lck-o1-UNE8dQ' Running [N0]: ltl2tgba -s '(!(X((a) U (b))))' >'lck-o0-coM8tH' Running [N1]: spin -f '(!(X((a) U (b))))' >'lck-o1-eHPoQy' Performing sanity checks and gathering statistics... no problem detected
ltlcross can only read two kinds of output:
- Never claims (only if they are restricted to representing an
automaton using
if,goto, andskipstatements) such as those output byspin,ltl2ba,ltl3ba, orltl2tgba --spin. These should be indicated using%N. - LBTT's format, which supports generalized Büchi automata with
either state-based acceptance or transition-based acceptance.
This output is used for instance by
lbt,modella, orltl2tgba --lbtt. These should be indicated using%T.
Of course all configured tools need not the same % sequences.
Getting statistics
Detailed statistics about the result of each translation, and the
product of that resulting automaton with the random state-space, can
be obtained using the --csv=FILE or --json=FILE option.
The following compare ltl2tgba, spin, and lbt on three random
formula (where W and M operators have been removed because they
are not supported by spin and lbt).
randltl -n 2 a b |
ltlfilt --remove-wm |
ltlcross --csv=results.csv \
'ltl2tgba -s %f >%N' \
'spin -f %s >%N' \
'lbt < %L >%T'-:1: (G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))) Running [P0]: ltl2tgba -s '(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1)))))))' >'lck-o0-eGEYaZ' Running [P1]: spin -f '([](((p0) U ((p0) && ([](p1)))) V (([](p1)) || ((p0) U ((p0) && ([](p1)))))))' >'lck-o1-nYpFBX' Running [P2]: lbt < 'lck-i0-fGdZQ0' >'lck-o2-CPs23V' Running [N0]: ltl2tgba -s '(!(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))))' >'lck-o0-kXiZZS' Running [N1]: spin -f '(!([](((p0) U ((p0) && ([](p1)))) V (([](p1)) || ((p0) U ((p0) && ([](p1))))))))' >'lck-o1-7ILLzR' Running [N2]: lbt < 'lck-i0-9KG0wU' >'lck-o2-CcMCaQ' Performing sanity checks and gathering statistics... -:2: (!((G(F(p0))) -> (F(p1)))) Running [P0]: ltl2tgba -s '(!((G(F(p0))) -> (F(p1))))' >'lck-o0-IOckzW' Running [P1]: spin -f '(!((<>(p1)) || (!([](<>(p0))))))' >'lck-o1-tsT3RZ' Running [P2]: lbt < 'lck-i1-5TJXmT' >'lck-o2-5E9jb3' Running [N0]: ltl2tgba -s '(G(F(p0))) -> (F(p1))' >'lck-o0-M3XRO9' Running [N1]: spin -f '(<>(p1)) || (!([](<>(p0))))' >'lck-o1-6nxqfd' Running [N2]: lbt < 'lck-i1-4hS5u6' >'lck-o2-vNItGg' Performing sanity checks and gathering statistics... no problem detected
After this execution, the file results.csv contains the following:
"formula", "tool", "states", "edges", "transitions", "acc", "scc", "nondetstates", "nondeterministic", "time", "product_states", "product_transitions", "product_scc" "(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1)))))))", "ltl2tgba -s %f >%N", 3, 5, 9, 1, 3, 2, 1, 0.0453898, 401, 5136, 3 "(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1)))))))", "spin -f %s >%N", 6, 13, 18, 1, 3, 6, 1, 0.0108596, 995, 14384, 5 "(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1)))))))", "lbt < %L >%T", 8, 41, 51, 1, 3, 8, 1, 0.00343479, 1389, 42998, 5 "(!(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))))", "ltl2tgba -s %f >%N", 4, 10, 16, 1, 3, 0, 0, 0.0437875, 797, 16340, 3 "(!(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))))", "spin -f %s >%N", 7, 24, 63, 1, 4, 6, 1, 0.0061535, 1400, 64668, 4 "(!(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))))", "lbt < %L >%T", 39, 286, 614, 3, 28, 33, 1, 0.00384434, 7592, 602204, 4400 "(!((G(F(p0))) -> (F(p1))))", "ltl2tgba -s %f >%N", 2, 4, 4, 1, 1, 0, 0, 0.0416853, 398, 4198, 1 "(!((G(F(p0))) -> (F(p1))))", "spin -f %s >%N", 2, 3, 5, 1, 1, 1, 1, 0.00325558, 398, 5227, 1 "(!((G(F(p0))) -> (F(p1))))", "lbt < %L >%T", 5, 10, 15, 1, 4, 5, 1, 0.00299424, 409, 6401, 12 "(G(F(p0))) -> (F(p1))", "ltl2tgba -s %f >%N", 3, 5, 11, 1, 3, 1, 1, 0.0422192, 600, 11663, 3 "(G(F(p0))) -> (F(p1))", "spin -f %s >%N", 3, 5, 14, 1, 3, 1, 1, 0.00293655, 600, 14840, 3 "(G(F(p0))) -> (F(p1))", "lbt < %L >%T", 11, 18, 54, 2, 11, 5, 1, 0.0030133, 1253, 26891, 457
This can be loaded in any spreadsheet application. Although we only
supplied 2 random generated formulas, the output contains 4 formulas because
ltlcross had to translate the positive and negative version of each.
If we had used the option --json=results.json instead of
--cvs=results.csv, the file results.json would have contained the
following JSON output.
{
"tools": [
"ltl2tgba -s %f >%N",
"spin -f %s >%N",
"lbt < %L >%T"
],
"inputs": [
"(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1)))))))",
"(!(G(((p0) U ((p0) & (G(p1)))) R ((G(p1)) | ((p0) U ((p0) & (G(p1))))))))",
"(!((G(F(p0))) -> (F(p1))))",
"(G(F(p0))) -> (F(p1))"
],
"fields": [
"input", "tool", "states", "edges", "transitions", "acc", "scc", "nondetstates", "nondeterministic", "time", "product_states", "product_transitions", "product_scc"
],
"results": [
[ 0, 0, 3, 5, 9, 1, 3, 2, 1, 0.0431589, 401, 5136, 3 ],
[ 0, 1, 6, 13, 18, 1, 3, 6, 1, 0.0104812, 995, 14384, 5 ],
[ 0, 2, 8, 41, 51, 1, 3, 8, 1, 0.00321619, 1389, 42998, 5 ],
[ 1, 0, 4, 10, 16, 1, 3, 0, 0, 0.0443761, 797, 16340, 3 ],
[ 1, 1, 7, 24, 63, 1, 4, 6, 1, 0.00623927, 1400, 64668, 4 ],
[ 1, 2, 39, 286, 614, 3, 28, 33, 1, 0.00386306, 7592, 602204, 4400 ],
[ 2, 0, 2, 4, 4, 1, 1, 0, 0, 0.0414639, 398, 4198, 1 ],
[ 2, 1, 2, 3, 5, 1, 1, 1, 1, 0.00327304, 398, 5227, 1 ],
[ 2, 2, 5, 10, 15, 1, 4, 5, 1, 0.00322862, 409, 6401, 12 ],
[ 3, 0, 3, 5, 11, 1, 3, 1, 1, 0.0432979, 600, 11663, 3 ],
[ 3, 1, 3, 5, 14, 1, 3, 1, 1, 0.00296043, 600, 14840, 3 ],
[ 3, 2, 11, 18, 54, 2, 11, 5, 1, 0.00295457, 1253, 26891, 457 ]
]
}
Here the fields table describes the columns of the results table,
and the input and tool columns contains indices relative to the
inputs and tools table. This format is more compact when dealing
with lots of translators and formulas, because they don't have to be
repeated on each line as in the CSV version.
JSON data can be easily processed in any language. For instance the
following Python3 script averages each column for each tool,
and presents the results in a form that can almost be copied into a
LaTeX table (the % in the tool names have to be taken care of).
#!/usr/bin/python3
import json
data = json.load(open('results.json'))
datacols = range(2, len(data["fields"]))
# Index results by tool
results = { t:[] for t in range(0, len(data["tools"])) }
for l in data["results"]:
results[l[1]].append(l)
# Average columns for each tools, and display them as a table
print("%-18s &" % "tool", "count &",
" & ".join(data["fields"][2:]), "\\\\")
for i in range(0, len(data["tools"])):
c = len(results[i])
sums = ["%6.2f" % (sum([x[j] for x in results[i]])/c)
for j in datacols]
print("%-18s & %3d & " % (data["tools"][i], c),
" & ".join(sums), "\\\\")tool & count & states & edges & transitions & acc & scc & nondetstates & nondeterministic & time & product_states & product_transitions & product_scc \\ ltl2tgba -s %f >%N & 4 & 3.00 & 6.00 & 10.00 & 1.00 & 2.50 & 0.75 & 0.50 & 0.04 & 549.00 & 9334.25 & 2.50 \\ spin -f %s >%N & 4 & 4.50 & 11.25 & 25.00 & 1.00 & 2.75 & 3.50 & 1.00 & 0.01 & 848.25 & 24779.75 & 3.25 \\ lbt < %L >%T & 4 & 15.75 & 88.75 & 183.50 & 1.75 & 11.50 & 12.75 & 1.00 & 0.00 & 2660.75 & 169623.50 & 1218.50 \\
The script bench/ltl2tgba/sum.py is a more evolved version of the
above script that generates two kinds of LaTeX tables.
When computing such statistics, you should be aware that inputs for
which a tool failed to generate an automaton (e.g. it crashed, or it
was killed if you used ltlcross's --timeout option to limit run
time) are not represented in the CSV or JSON files. However data for
bogus automata are still included: as shown below ltlcross will
report inconsistencies between automata as errors, but it does not try
to guess who is incorrect.
Detecting problems
If a translator exits with a non-zero status code, or fails to output
an automaton ltlcross can read, and error will be displayed and the
result of the translation will be discarded.
Otherwise ltlcross performs the following checks on all translated
formulas ($P_i$ and $N_i$ designate respectively the translation of
positive and negative formulas by the ith translator).
-
Intersection check: $P_i\otimes N_j$ must be empty for all pairs of $(i,j)$.
A single failing translator might generate a lot of lines of the form:
error: P0*N1 is nonempty error: P1*N0 is nonempty error: P1*N1 is nonempty error: P1*N2 is nonempty error: P1*N3 is nonempty error: P1*N4 is nonempty error: P1*N5 is nonempty error: P1*N6 is nonempty error: P1*N7 is nonempty error: P1*N8 is nonempty error: P1*N9 is nonempty error: P2*N1 is nonempty error: P3*N1 is nonempty error: P4*N1 is nonempty error: P5*N1 is nonempty error: P6*N1 is nonempty error: P7*N1 is nonempty error: P8*N1 is nonempty error: P9*N1 is nonempty
In this example, translator number
1looks clearly faulty (at least the other 9 translators do not contradict each other). -
Cross-comparison checks: for some state-space $S$, all $P_i\otimes S$ are either all empty, or all non-empty. Similarly all $N_i\otimes S$ are either all empty, or all non-empty.
A cross-comparison failure could be displayed as:
error: {P0,P2,P3,P4,P5,P6,P7,P8,P9} disagree with {P1} when evaluating the state-space -
Consistency check:
For each $i$, the products $P_i\otimes S$ and $N_i\otimes S$ actually cover all states of $S$. Because $S$ does not have any deadlock, any of its infinite path must be accepted by $P_i$ or $N_i$ (or both).
An error in that case is displayed as
error: inconsistency between P1 and N1
The above checks are the same that are performed by LBTT.
If any problem was reported during the translation of one of the
formulas, ltlcheck will exit with an exit status of 1. Statistics
(if requested) are output nonetheless, and include any faulty
automaton as well.
Miscellaneous options
--stop-on-error
The --stop-on-error will cause ltlcross to abort on the first
detected error. This include failure to start some translator, read
its output, or failure to passe the sanity checks. Timeouts are
allowed.
One use for this option is when ltlcross is used in combination with
randltl to check translators on an infinite stream of formulas.
For instance the following will cross-compare ltl2tgba against
ltl3ba until it finds an error, or your interrupt the command, or it
runs out of memory (the hash tables used by randltl and ltlcross
to remove duplicate formulas will keep growing).
randltl -n -1 --tree-size 10..25 a b c | ltlcross --stop-on-error 'ltl2tgba --lbtt %f >%T' 'ltl3ba -f %s >%N'
--no-check
The --no-check option disables all sanity checks, and only use the supplied
formulas in their positive form.
When checks are enabled, the negated formulas are intermixed with the
positives ones in the results. Therefore the --no-check option can
be used to gather statistics about a specific set of formulas.