rlauxe
Belgium election use case
06/20/2026
Viewing the Belgium 2024 election interactively
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clone the latest repos of both rlauxe (https://github.com/JohnLCaron/rlauxe-viewer) and rlauxe-viewer (https://github.com/JohnLCaron/rlauxe-viewer)
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to generate the data, follow these instructions from https://github.com/JohnLCaron/rlauxe/blob/main/docs/Developer.md#generate-test-cases-from-the-uber-jar
build the uberjars:
$ cd <devhome>/rlauxe
$ ./gradlew clean assemble uberjar
for the belgium test case, the repo contains the needed input for belgium2024 election. To create the data:
$ java -classpath cases/build/libs/cases-0.9.5.3-uber.jar org.cryptobiotic.rlauxe.cli.CreateCaseData \
-case belgium -topdir "/home/you/wherever/cases/belgium2024"
- check cases/build/libs/ for the latest version of cases-
-uber.jar and use that version - substitute your own output “topdir” directory
- to run the viewer, follow these instructions from https://github.com/JohnLCaron/rlauxe-viewer#starting-rlauxe-viewer
$ cd <devhome>/rlauxe-viewer
$ ./gradlew clean assemble uberJar
$ java -jar viewer/build/libs/viewer-uber.jar -belgiumAudit
Also see https://github.com/JohnLCaron/rlauxe-viewer#special-features-for-belgium-audits
This will work whenever theres a new version of the data format or the viewer. Always update both repos at the same time.
2024 Data
Downloaded the summary data in json from https://resultatselection.belgium.be/fr/search/chambre-des-repr%C3%A9sentants/2024/circonscription-%C3%A9lectorale
and placed in cases/src/test/data/belgium2024.
Olivier’s python code is at https://git-crypto.elen.ucl.ac.be/opereira/rlabelgium
Creating the election
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Set testdataDir in core/src/testFixtures/kotlin/org/cryptobiotic/rlauxe/TestUtils.kt to a convenient location on your local machine.
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Using cases/src/test/kotlin/org/cryptobiotic/rlauxe/util/TestGenerateAllUseCases.kt, run createAllBelgiumElections() to create all the elections.
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The elections will be created under toptopdir = $testdataDir/cases/belgium/2024/.
View all results in rlauxe-viewer by pointing to $toptopDir, or an individual contest by pointing to $toptopDir/$contestName/audit.
Details
- Each contest creates its own set of cvrs by creating one cvr for each vote in the election.
- It also creates mvrs from the cvrs for use in the audit. The default is to just copy the cvrs, so there are no errors.
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You can also generate the mvrs with some “fuzz” amount by changing line ~57 in CreateBelgiumClca
clcaConfig = ClcaConfig(fuzzMvrs=0.0) - Note that while we often use “percent fuzz”, its actually the ratio of fuzz to the total ballots, so fuzzMvrs=.001 means .1 %. We are finding that close D’Hondt elections should be <= .001 fuzz. Really, we need to aim for no errors at all.
Also see D’Hondt notes
Results from running Belgium elections with no errors
Samples Needed across all assertions
In all 426 assertions in Belgium 2024 election, only 13 need more than 1000 samples:
Because upper varies for each assorter, noerror = 1/(2-margin/upper) is much better to plot against. Furthermore, when there are no errors, samplesNeeded depends only on noerror: samplesNeeded = -ln(alpha) / ln(1 + maxBet * (noerror − 1/2)), which is why the plot is smooth.
Results from createAllBelgiumElections()
| minAssorter | noerror | mean | upper | nmvrs | minMvrs | pct % |
Anvers | DHondt w/l='CD&V'/'PVDA' | 0.500134 | 0.500267 | 1.000000 | 12383 | 11203 | 1.04 % |
Bruxelles | DHondt w/l='PS'/'MR' | 0.500210 | 0.500472 | 1.125000 | 7870 | 7137 | 1.52 % |
FlandreWest | DHondt w/l='PVDA'/'CD&V' | 0.501659 | 0.506614 | 2.000000 | 1005 | 904 | 0.12 % |
FlandreEast | DHondt w/l='Vooruit'/'CD&V' | 0.500455 | 0.500908 | 1.000000 | 3657 | 3296 | 0.35 % |
Hainaut | BelowThreshold for 'ECOLO' | 0.500164 | 0.500173 | 0.526316 | 10083 | 9136 | 1.36 % |
Liège | DHondt w/l='LES ENGAGÉS'/'PS' | 0.500284 | 0.500663 | 1.166667 | 5826 | 5267 | 0.92 % |
Limbourg | DHondt w/l='Vooruit'/'VLAAMS BELANG' | 0.502437 | 0.507277 | 1.500000 | 684 | 616 | 0.12 % |
Luxembourg | DHondt w/l='LES ENGAGÉS'/'MR' | 0.503001 | 0.505966 | 1.000000 | 556 | 501 | 0.32 % |
Namur | DHondt w/l='PTB'/'PS' | 0.505404 | 0.516037 | 1.500000 | 310 | 279 | 0.10 % |
BrabantFlamant | DHondt w/l='VLAAMS BELANG'/'N-VA' | 0.504228 | 0.511180 | 1.333333 | 396 | 356 | 0.06 % |
BrabantWallon | DHondt w/l='MR'/'LES ENGAGÉS' | 0.502644 | 0.504384 | 0.833333 | 631 | 568 | 0.25 % |
Notes:
- Hainaut fails when simFuzz = .001 because its margin is so small.
- To look at all the elections with rlauxe-viewer
- run createAllBelgiumElections() which puts all elections under toptopdir = “$testdataDir/cases/belgium/2024”
- open $toptopdir in rlauxe-viewer
Results from createBelgiumElection(“Anvers”)
showBelgiumElection Anvers
DHondtContest 'Anvers' (1) DHONDT voteForN=1 votes={6=368877, 1=249826, 5=127973, 8=125894, 4=125257, 7=90370, 2=70890, 10=10341, 9=8639, 11=7221, 3=4213, 12=1686} undervotes=0, voteForN=1
winners=[6, 1, 5, 8, 4, 7, 2] Nc=1191187 Nphantoms=0 Nu=0 sumVotes=1191187
nseats=24 winners={6=8, 1=5, 5=3, 8=3, 4=2, 7=2, 2=1} belowMin=[3, 9, 10, 11, 12] threshold=0.05 minVotes=59560
fw/fl=41964.7/41752.3 diff=212 (w-l)/w =0.00506 Npop=1191187 dilutedMargin=0.0535% reportedMargin=0.0535% recountMargin=0.5060%
candidate Round: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
1 VLAAMS BELANG : 249826 (2) | 124913 (7) | 83275 (11) | 62456 (17) | 49965 (20) | 41637 | 35689 | 31228 | 27758 |
2 open vld : 70890 (13) | 35445 | 23630 | 17722 | 14178 | 11815 | 10127 | 8861 | 7876 |
3 Volt Europa*: 4213 | 2106 | 1404 | 1053 | 842 | 702 | 601 | 526 | 468 |
4 PVDA : 125257 (6) | 62628 (16) | 41752 | 31314 | 25051 | 20876 | 17893 | 15657 | 13917 |
5 Vooruit : 127973 (4) | 63986 (14) | 42657 (23) | 31993 | 25594 | 21328 | 18281 | 15996 | 14219 |
6 N-VA : 368877 (1) | 184438 (3) | 122959 (8) | 92219 (9) | 73775 (12) | 61479 (18) | 52696 (19) | 46109 (21) | 40986 |
7 GROEN : 90370 (10) | 45185 (22) | 30123 | 22592 | 18074 | 15061 | 12910 | 11296 | 10041 |
8 CD&V : 125894 (5) | 62947 (15) | 41964 (24) | 31473 | 25178 | 20982 | 17984 | 15736 | 13988 |
9 Voor U*: 8639 | 4319 | 2879 | 2159 | 1727 | 1439 | 1234 | 1079 | 959 |
10 DierAnimal*: 10341 | 5170 | 3447 | 2585 | 2068 | 1723 | 1477 | 1292 | 1149 |
11 Partij BLANCO*: 7221 | 3610 | 2407 | 1805 | 1444 | 1203 | 1031 | 902 | 802 |
12 BELG.UNIE-BUB*: 1686 | 843 | 562 | 421 | 337 | 281 | 240 | 210 | 187 |
* failed threshold
minAssorter: DHondt w/l='CD&V'/'PVDA': dilutedMean=50.0267% upperBound=1.0000
fw/fl=41964.7/41752.3 diff=212 (w-l)/w =0.00506
Show Anvers Contest in rlauxe-viewer
| field | value | description |
| ---------- | -------------------- | ----------------------------------------- |
| round | 1 | index of audit round |
| id | 1 | contest identifier |
| name | Anvers | contest name |
| type | DHONDT | contest type |
| margin | 5.347607050782965E-4 | diluted margin (smallest assertion) |
| estNewMvrs | 12383 | estimated new samples needed |
| estMvrs | 12383 | estimated samples needed |
| mvrsUsed | 12383 | number of mvrs actually used during audit |
| mvrsExtra | 0 | estimated - used |
| include | true | include the contest in this audit round |
| done | true | contest has completed |
| status | Success | status of contest completion |
DHondtContest 'Anvers' (1) DHONDT voteForN=1 votes={6=368877, 1=249826, 5=127973, 8=125894, 4=125257, 7=90370, 2=70890, 10=10341, 9=8639, 11=7221, 3=4213, 12=1686} undervotes=0, voteForN=1
winners=[6, 1, 5, 8, 4, 7, 2] Nc=1191187 Nphantoms=0 Nu=0 sumVotes=1191187
nseats=24 winners={6=8, 1=5, 5=3, 8=3, 4=2, 7=2, 2=1} belowMin=[3, 9, 10, 11, 12] threshold=0.05 minVotes=59560
fw/fl=41964.7/41752.3 diff=212 (w-l)/w =0.00506 Npop=1191187 dilutedMargin=0.0535% reportedMargin=0.0535% recountMargin=0.5060%
candidate Round: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
1 VLAAMS BELANG : 249826 (2) | 124913 (7) | 83275 (11) | 62456 (17) | 49965 (20) | 41637 | 35689 | 31228 | 27758 |
2 open vld : 70890 (13) | 35445 | 23630 | 17722 | 14178 | 11815 | 10127 | 8861 | 7876 |
3 Volt Europa*: 4213 | 2106 | 1404 | 1053 | 842 | 702 | 601 | 526 | 468 |
4 PVDA : 125257 (6) | 62628 (16) | 41752 | 31314 | 25051 | 20876 | 17893 | 15657 | 13917 |
5 Vooruit : 127973 (4) | 63986 (14) | 42657 (23) | 31993 | 25594 | 21328 | 18281 | 15996 | 14219 |
6 N-VA : 368877 (1) | 184438 (3) | 122959 (8) | 92219 (9) | 73775 (12) | 61479 (18) | 52696 (19) | 46109 (21) | 40986 |
7 GROEN : 90370 (10) | 45185 (22) | 30123 | 22592 | 18074 | 15061 | 12910 | 11296 | 10041 |
8 CD&V : 125894 (5) | 62947 (15) | 41964 (24) | 31473 | 25178 | 20982 | 17984 | 15736 | 13988 |
9 Voor U*: 8639 | 4319 | 2879 | 2159 | 1727 | 1439 | 1234 | 1079 | 959 |
10 DierAnimal*: 10341 | 5170 | 3447 | 2585 | 2068 | 1723 | 1477 | 1292 | 1149 |
11 Partij BLANCO*: 7221 | 3610 | 2407 | 1805 | 1444 | 1203 | 1031 | 902 | 802 |
12 BELG.UNIE-BUB*: 1686 | 843 | 562 | 421 | 337 | 281 | 240 | 210 | 187 |
* failed threshold