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Radixor/docs/benchmarks/languages/polish.md
Leo Galambos 05f3855b99 feat(benchmarks): expand multilingual stemming quality evaluation 
* cover all Radixor dictionary languages
* add PRIMARY_OUTPUT, ANY_CANDIDATE, and ALL_CANDIDATES policies
* measure pairwise over-stemming and under-stemming
* add balanced accuracy and complementary quality metrics
* compare single-output and multi-output stemmers fairly
* improve result validation, reporting, and documentation
* move stemming quality tests into the standard test source set
* preserve the existing JMH benchmark structure and badge output
2026-07-20 23:20:17 +02:00

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Polish Stemmer Benchmarks

This page reports same-language stemming benchmarks for Polish. Accuracy is listed first because speed without root agreement is not enough to interpret stemmer quality.

All speed values are environment-specific and were measured on the hardware and JVM listed in the benchmark overview. Speed benchmark operations process changed dictionary tokens only. Accuracy uses the complete Radixor dictionary for the language.

Radixor must not be read as simply "slower" when a narrow competitor has a lower timing row. In these tables Radixor is the quality-oriented baseline: its exact-root accuracy is typically close to 100%, while many faster rule-based, light, minimal, or possessive filters reach that speed by doing much less linguistic work and often score far lower in All exact and Changed exact. The Radixor rows in this benchmark refresh use the contracted compiled patch trie: compilation collapses uniform patch-command subtrees into accepting leaves, reducing hot lookup depth while preserving the preferred stemming result measured by the accuracy pass. The EnglishRadixorDictionaryCoverageBenchmark table shows the resulting quality/speed envelope explicitly. The same interpretation applies to this language page: speed rows must be read together with the accuracy table above them.

Dictionary Corpus

Resource Dictionary rows Complete quality tokens Already-root tokens Changed speed tokens
PL_PL 9,990 132,308 19,957 112,351

Radixor Patch Command Distribution

Radixor stores the preferred transformation for each normalized dictionary word form as a compiled patch command. This distribution shows which runtime command class is selected by the trained trie for the complete language dictionary. The total number of preferred patch commands analyzed for this language is 132,308.

Command class Meaning Word forms Share
AppendCharacterCommand Appends one character to the end of the word form. 1,719 1.299%
BackwardCompoundCommand Applies a multi-step backward patch made from skip, delete, insert, and replace operations. 53,303 40.287%
DeleteSuffixCommand Deletes one or more trailing characters from the word form. 37,051 28.004%
PreserveCommand Returns the word form unchanged because it already matches the preferred root. 20,415 15.430%
ReplaceLastCharacterCommand Replaces the final character of the word form. 19,820 14.980%

Accuracy

Accuracy is computed from JMH auxiliary counters in the current report. The counters are deterministic for a fixed corpus and stemmer; percentages divide matching counters by evaluated counters from the same report and are not timing metrics.

Stemmer All exact Changed exact Root preserved Note
Radixor 98.837% 98.744% 99.359% Full Radixor dictionary patch-command stemmer.
Lucene HunspellStemFilter 89.545% 88.272% 96.713% Benchmark-only Polish Hunspell dictionary compared via Lucene HunspellStemFilter.
Lucene MorfologikFilter 87.729% 86.606% 94.047% Dictionary-based path; Morfologik can emit multiple terms.
Lucene StempelFilter 70.009% 69.262% 74.220% Lucene TokenFilter integration path for table-driven Polish Stempel.
Lucene StempelStemmer direct 70.009% 69.262% 74.220% Direct table-driven Polish Stempel stemmer API.

Speed

Speed uses JMH average time, 3 warmup iterations, 5 measurement iterations, 1 fork, and 1 thread. Relative factor is computed against the single Radixor row on this language page. Values below 1.000 are faster than that Radixor baseline; values above 1.000 are slower.

Stemmer Benchmark method Score ms/op Error ms ns/token Relative vs Radixor Note
Radixor polishRadixor 9.049 0.485 80.5 1.000 Full Radixor dictionary patch-command stemmer.
Lucene HunspellStemFilter luceneHunspellStemFilter 483.316 11.455 4301.8 53.408 Benchmark-only Polish Hunspell dictionary compared via Lucene HunspellStemFilter.
Lucene StempelStemmer direct polishLuceneStempelStemmerDirect 41.932 1.916 373.2 4.634 Direct table-driven Polish Stempel stemmer API.
Lucene StempelFilter polishLuceneStempelFilter 45.277 13.693 403.0 5.003 Lucene TokenFilter integration path for table-driven Polish Stempel.
Lucene MorfologikFilter polishLuceneMorfologikFilter 135.763 31.634 1208.4 15.002 Dictionary-based Morfologik TokenFilter; may emit multiple terms.

Interpretation Notes

  • Radixor is a dictionary-derived patch-command stemmer. Its quality depends on the language resource used to train the compiled trie.
  • Light, minimal, plural, and possessive filters are narrow baselines. They can be fast because they intentionally perform less linguistic work.
  • Lucene TokenFilter rows include TokenStream, attribute, and required normalization overhead. Direct rows measure exposed direct APIs.
  • Morfologik rows are dictionary-based and can emit multiple terms for one input token. Quality rows use the first returned term when no ranking weight is available.
  • Snowball rows are rule-based generated suffix stemmers; they are useful algorithmic baselines, not dictionary-root equivalence guarantees.

Stemming Quality

Runtime performance and linguistic grouping quality are independent dimensions. This section evaluates language PL_PL using the complete validated stemming-quality result matrix. Every usable dictionary row is one gold-standard group of forms expected to share a morphological family or lemma. Exact equality with a predetermined lemma is not required. Same-row pairs are positive pairs; pairs from different rows are negative pairs.

ALL_WORDS includes every valid group and its original forms. LOWERCASE_GROUPS_ONLY excludes an entire group when any Unicode code point is uppercase or titlecase; retained words are not lowercased or otherwise rewritten. This isolates case-handling effects without changing retained inputs. Download the complete machine-readable result snapshot.

Evaluation Scope and Key Findings

The dictionary resource is src/main/resources/pl_pl/stemmer.gz. The following findings compare only deterministic PRIMARY_OUTPUT rows over identical included groups; candidate policies are reported separately as capability analyses.

  • ALL_WORDS: Radixor ranks first by balanced accuracy at 0.990388 among 5 deterministic stemmers. The runner-up is POLISH LUCENE MORFOLOGIK FILTER at 0.948154, a difference of 0.042234. This rank does not imply leadership in throughput or every secondary metric.
  • LOWERCASE_GROUPS_ONLY: Radixor ranks first by balanced accuracy at 0.990579 among 5 deterministic stemmers. The runner-up is POLISH LUCENE MORFOLOGIK FILTER at 0.948177, a difference of 0.042402. This rank does not imply leadership in throughput or every secondary metric.

ALL_WORDS

This mode contains 11 result rows, 5 evaluated stemmers, and 3 output policies. Applied-row and form counts are shown per row because adapters share the language corpus but policy rows remain independently auditable. Rankings are separated by output policy and ordered by unrounded balanced accuracy, followed by MCC, F1, over-stemming rate, over-stemming count, under-stemming rate, and stemmer. Balanced accuracy is a navigation metric, not a universally authoritative quality score.

PRIMARY_OUTPUT ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor PRIMARY_OUTPUT 0.990388 13669 / 7482478003 (0.000183%) 21547 / 1120967 (1.922180%) 0.986324 0.984237 0.984241
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.948154 99228 / 7482478003 (0.001326%) 116220 / 1120967 (10.367834%) 0.907324 0.903167 0.903179
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.933222 52652 / 7482478003 (0.000704%) 149705 / 1120967 (13.354987%) 0.930930 0.905656 0.906571
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.855748 66669 / 7482478003 (0.000891%) 323394 / 1120967 (28.849556%) 0.871106 0.803515 0.810296
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.855748 66669 / 7482478003 (0.000891%) 323394 / 1120967 (28.849556%) 0.871106 0.803515 0.810296
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor PRIMARY_OUTPUT 0.987720 0.980778 0.999998 0.990388 0.999995 0.000005
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.910118 0.896322 0.999987 0.948154 0.999971 0.000029
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.948578 0.866450 0.999993 0.933222 0.999973 0.000027
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.922858 0.711504 0.999991 0.855748 0.999948 0.000052
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.922858 0.711504 0.999991 0.855748 0.999948 0.000052
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor PRIMARY_OUTPUT 0.986324 0.984237 0.982159 0.968963 0.984243 0.984241
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.907324 0.903167 0.899047 0.823432 0.903193 0.903179
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.930930 0.905656 0.881718 0.827579 0.906584 0.906571
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.871106 0.803515 0.745659 0.671564 0.810320 0.810296
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.871106 0.803515 0.745659 0.671564 0.810320 0.810296
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor PRIMARY_OUTPUT 0.984234 0.996967 0.996469 0.996718 0.996718
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.903153 0.990022 0.977054 0.983495 0.983495
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.905642 0.994546 0.970520 0.982386 0.982386
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.803490 0.991767 0.931069 0.960460 0.960460
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.803490 0.991767 0.931069 0.960460 0.960460
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor PRIMARY_OUTPUT 1099420 13669 21547 7482464334 13669 / 7482478003 21547 / 1120967
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 1004747 99228 116220 7482378775 99228 / 7482478003 116220 / 1120967
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 971262 52652 149705 7482425351 52652 / 7482478003 149705 / 1120967
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 797573 66669 323394 7482411334 66669 / 7482478003 323394 / 1120967
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 797573 66669 323394 7482411334 66669 / 7482478003 323394 / 1120967

ANY_CANDIDATE ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor ANY_CANDIDATE 1.000000 0 / 7482478003 (0.000000%) 0 / 1120967 (0.000000%) 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.987570 85532 / 7482478003 (0.001143%) 27855 / 1120967 (2.484908%) 0.936598 0.950693 0.950985
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.963982 42213 / 7482478003 (0.000564%) 80743 / 1120967 (7.202977%) 0.954209 0.944197 0.944333
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ANY_CANDIDATE 1.000000 1.000000 1.000000 1.000000 1.000000 0.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.927432 0.975151 0.999989 0.987570 0.999985 0.000015
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.961002 0.927970 0.999994 0.963982 0.999984 0.000016
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor ANY_CANDIDATE 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.936598 0.950693 0.965218 0.906020 0.950992 0.950985
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.954209 0.944197 0.934394 0.894293 0.944342 0.944333
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor ANY_CANDIDATE n/a n/a n/a n/a n/a
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE n/a n/a n/a n/a n/a
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE n/a n/a n/a n/a n/a
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ANY_CANDIDATE 1120967 0 0 7482478003 0 / 7482478003 0 / 1120967
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 1093112 85532 27855 7482392471 85532 / 7482478003 27855 / 1120967
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 1040224 42213 80743 7482435790 42213 / 7482478003 80743 / 1120967

ALL_CANDIDATES ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor ALL_CANDIDATES 0.999997 38073 / 7482478003 (0.000509%) 0 / 1120967 (0.000000%) 0.973547 0.983301 0.983436
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.987566 143096 / 7482478003 (0.001912%) 27855 / 1120967 (2.484908%) 0.901045 0.927476 0.928576
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.963980 82745 / 7482478003 (0.001106%) 80743 / 1120967 (7.202977%) 0.926646 0.927142 0.927132
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ALL_CANDIDATES 0.967151 1.000000 0.999995 0.999997 0.999995 0.000005
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.884246 0.975151 0.999981 0.987566 0.999977 0.000023
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.926316 0.927970 0.999989 0.963980 0.999978 0.000022
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor ALL_CANDIDATES 0.973547 0.983301 0.993253 0.967151 0.983438 0.983436
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.901045 0.927476 0.955505 0.864761 0.928587 0.928576
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.926646 0.927142 0.927639 0.864180 0.927143 0.927132
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor ALL_CANDIDATES n/a n/a n/a n/a n/a
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES n/a n/a n/a n/a n/a
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES n/a n/a n/a n/a n/a
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ALL_CANDIDATES 1120967 38073 0 7482439930 38073 / 7482478003 0 / 1120967
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 1093112 143096 27855 7482334907 143096 / 7482478003 27855 / 1120967
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 1040224 82745 80743 7482395258 82745 / 7482478003 80743 / 1120967

Multi-output analysis

Alternative candidates are capability analyses, not replacements for the deterministic comparison.

Stemmer Under pairs repaired Best-case over pairs avoided All-candidate collisions added Multi-candidate forms Multi-candidate share Maximum candidates Total candidate assignments
HUNSPELL POLISH LUCENE FILTER 68962 10439 30093 11447 9.356634% 6 135231
POLISH LUCENE MORFOLOGIK FILTER 88365 13696 43868 12873 10.522229% 5 136636
Radixor 21547 13669 24404 2866 2.342632% 4 125778

LOWERCASE_GROUPS_ONLY

This mode contains 11 result rows, 5 evaluated stemmers, and 3 output policies. Applied-row and form counts are shown per row because adapters share the language corpus but policy rows remain independently auditable. Rankings are separated by output policy and ordered by unrounded balanced accuracy, followed by MCC, F1, over-stemming rate, over-stemming count, under-stemming rate, and stemmer. Balanced accuracy is a navigation metric, not a universally authoritative quality score.

PRIMARY_OUTPUT ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor PRIMARY_OUTPUT 0.990579 13669 / 7310252699 (0.000187%) 21000 / 1114651 (1.883998%) 0.986350 0.984397 0.984400
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.948177 99224 / 7310252699 (0.001357%) 115513 / 1114651 (10.363154%) 0.906972 0.902966 0.902976
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.933309 51950 / 7310252699 (0.000711%) 148667 / 1114651 (13.337538%) 0.931269 0.905928 0.906847
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.856382 66274 / 7310252699 (0.000907%) 320158 / 1114651 (28.722712%) 0.871591 0.804380 0.811082
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.856382 66274 / 7310252699 (0.000907%) 320158 / 1114651 (28.722712%) 0.871591 0.804380 0.811082
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor PRIMARY_OUTPUT 0.987656 0.981160 0.999998 0.990579 0.999995 0.000005
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.909662 0.896368 0.999986 0.948177 0.999971 0.000029
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.948965 0.866625 0.999993 0.933309 0.999973 0.000027
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.923006 0.712773 0.999991 0.856382 0.999947 0.000053
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.923006 0.712773 0.999991 0.856382 0.999947 0.000053
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor PRIMARY_OUTPUT 0.986350 0.984397 0.982452 0.969274 0.984403 0.984400
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.906972 0.902966 0.898996 0.823098 0.902991 0.902976
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.931269 0.905928 0.881929 0.828033 0.906861 0.906847
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.871591 0.804380 0.746792 0.672772 0.811106 0.811082
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.871591 0.804380 0.746792 0.672772 0.811106 0.811082
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor PRIMARY_OUTPUT 0.984395 0.996926 0.996647 0.996786 0.996786
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 0.902952 0.989889 0.977012 0.983408 0.983408
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 0.905914 0.994584 0.970514 0.982402 0.982402
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 0.804354 0.991711 0.931318 0.960566 0.960566
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 0.804354 0.991711 0.931318 0.960566 0.960566
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor PRIMARY_OUTPUT 1093651 13669 21000 7310239030 13669 / 7310252699 21000 / 1114651
2 POLISH LUCENE MORFOLOGIK FILTER PRIMARY_OUTPUT 999138 99224 115513 7310153475 99224 / 7310252699 115513 / 1114651
3 HUNSPELL POLISH LUCENE FILTER PRIMARY_OUTPUT 965984 51950 148667 7310200749 51950 / 7310252699 148667 / 1114651
4 POLISH LUCENE STEMPEL DIRECT PRIMARY_OUTPUT 794493 66274 320158 7310186425 66274 / 7310252699 320158 / 1114651
5 POLISH LUCENE STEMPEL FILTER PRIMARY_OUTPUT 794493 66274 320158 7310186425 66274 / 7310252699 320158 / 1114651

ANY_CANDIDATE ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor ANY_CANDIDATE 1.000000 0 / 7310252699 (0.000000%) 0 / 1114651 (0.000000%) 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.987661 85532 / 7310252699 (0.001170%) 27494 / 1114651 (2.466602%) 0.936331 0.950586 0.950885
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.963946 41671 / 7310252699 (0.000570%) 80368 / 1114651 (7.210149%) 0.954406 0.944290 0.944429
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ANY_CANDIDATE 1.000000 1.000000 1.000000 1.000000 1.000000 0.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.927063 0.975334 0.999988 0.987661 0.999985 0.000015
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.961271 0.927899 0.999994 0.963946 0.999983 0.000017
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor ANY_CANDIDATE 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 0.936331 0.950586 0.965282 0.905826 0.950892 0.950885
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 0.954406 0.944290 0.934386 0.894459 0.944437 0.944429
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor ANY_CANDIDATE n/a n/a n/a n/a n/a
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE n/a n/a n/a n/a n/a
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE n/a n/a n/a n/a n/a
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ANY_CANDIDATE 1114651 0 0 7310252699 0 / 7310252699 0 / 1114651
2 POLISH LUCENE MORFOLOGIK FILTER ANY_CANDIDATE 1087157 85532 27494 7310167167 85532 / 7310252699 27494 / 1114651
3 HUNSPELL POLISH LUCENE FILTER ANY_CANDIDATE 1034283 41671 80368 7310211028 41671 / 7310252699 80368 / 1114651

ALL_CANDIDATES ranking

Rank Stemmer Output policy Balanced accuracy Over-stemming Under-stemming F0.5 F1 MCC
1 Radixor ALL_CANDIDATES 0.999997 38073 / 7310252699 (0.000521%) 0 / 1114651 (0.000000%) 0.973401 0.983208 0.983344
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.987657 143085 / 7310252699 (0.001957%) 27494 / 1114651 (2.466602%) 0.900618 0.927255 0.928372
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.963944 81865 / 7310252699 (0.001120%) 80368 / 1114651 (7.210149%) 0.926903 0.927276 0.927265
Classification metrics
Rank Stemmer Output policy Precision Recall Specificity Balanced accuracy Pairwise accuracy Error rate
1 Radixor ALL_CANDIDATES 0.966971 1.000000 0.999995 0.999997 0.999995 0.000005
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.883694 0.975334 0.999980 0.987657 0.999977 0.000023
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.926654 0.927899 0.999989 0.963944 0.999978 0.000022
Pair-relation metrics
Rank Stemmer Output policy F0.5 F1 F2 Jaccard Fowlkes–Mallows MCC
1 Radixor ALL_CANDIDATES 0.973401 0.983208 0.993215 0.966971 0.983347 0.983344
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 0.900618 0.927255 0.955516 0.864376 0.928384 0.928372
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 0.926903 0.927276 0.927649 0.864412 0.927276 0.927265
Partition metrics (PRIMARY_OUTPUT only)
Rank Stemmer Output policy Adjusted Rand Index Homogeneity Completeness V-measure Normalized mutual information
1 Radixor ALL_CANDIDATES n/a n/a n/a n/a n/a
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES n/a n/a n/a n/a n/a
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES n/a n/a n/a n/a n/a
Raw pair counts
Rank Stemmer Output policy TP FP FN TN Over error / possible Under error / possible
1 Radixor ALL_CANDIDATES 1114651 38073 0 7310214626 38073 / 7310252699 0 / 1114651
2 POLISH LUCENE MORFOLOGIK FILTER ALL_CANDIDATES 1087157 143085 27494 7310109614 143085 / 7310252699 27494 / 1114651
3 HUNSPELL POLISH LUCENE FILTER ALL_CANDIDATES 1034283 81865 80368 7310170834 81865 / 7310252699 80368 / 1114651

Multi-output analysis

Alternative candidates are capability analyses, not replacements for the deterministic comparison.

Stemmer Under pairs repaired Best-case over pairs avoided All-candidate collisions added Multi-candidate forms Multi-candidate share Maximum candidates Total candidate assignments
HUNSPELL POLISH LUCENE FILTER 68299 10279 29915 11265 9.315692% 6 133595
POLISH LUCENE MORFOLOGIK FILTER 88019 13692 43861 12763 10.554476% 5 135105
Radixor 21000 13669 24404 2780 2.298946% 4 124274

Output Policies and Metric Definitions

PRIMARY_OUTPUT uses one deterministic stem per form and therefore defines a strict partition. ANY_CANDIDATE is an optimistic oracle-assisted pairwise upper bound: a same-group pair succeeds when candidates intersect, while a different-group pair succeeds when a non-colliding selection exists. Candidate choices may differ between pairs, so this is not deterministic runtime behaviour and need not represent one globally consistent assignment. ALL_CANDIDATES activates every returned candidate; forms are related when candidate sets intersect. Alternatives can reduce under-stemming but can introduce cross-group collisions, and the resulting relation can overlap and need not be a partition.

For each row, TP = underPossiblePairs - underErrorPairs, FN = underErrorPairs, FP = overErrorPairs, and TN = overPossiblePairs - overErrorPairs. TP and FN concern same-group pairs; FP and TN concern different-group pairs. Consequently, under-stemming and over-stemming use different denominators. Undefined values are rendered as n/a.

  • Under-stemming rate: FN / (TP + FN), the false-negative rate over same-group pairs.
  • Over-stemming rate: FP / (TN + FP), the false-positive rate over different-group pairs.
  • Pairwise precision: TP / (TP + FP), the fraction of predicted conflations that are gold-standard positive pairs.
  • Pairwise recall: TP / (TP + FN), the fraction of gold-standard positive pairs successfully connected.
  • Pairwise specificity: TN / (TN + FP), the fraction of different-group pairs correctly separated.
  • Balanced accuracy: (recall + specificity) / 2. It gives equal weight to positive and negative pair classes and is less dominated by the large true-negative class than ordinary accuracy. It does not replace the raw errors or other metrics.
  • Pairwise F-beta: ((1 + betaSquared) * TP) / (((1 + betaSquared) * TP) + (betaSquared * FN) + FP). F0.5 emphasizes precision and penalizes over-stemming more; F1 weights precision and recall equally; F2 emphasizes recall and penalizes under-stemming more.
  • MCC: (TP * TN - FP * FN) / sqrt((TP + FP) * (TP + FN) * (TN + FP) * (TN + FN)). It uses all confusion counts and remains useful under class imbalance, except when its denominator is degenerate.
  • Jaccard index: TP / (TP + FP + FN).
  • Fowlkes–Mallows index: sqrt(precision * recall).
  • Pairwise accuracy: (TP + TN) / (TP + TN + FP + FN). It can be dominated by true-negative cross-group pairs.
  • Pairwise error rate: (FP + FN) / (TP + TN + FP + FN).

Adjusted Rand Index uses the gold/predicted contingency table and chance correction. Homogeneity is 1 - H(gold | predicted) / H(gold); completeness is 1 - H(predicted | gold) / H(predicted); V-measure is their harmonic mean; normalized mutual information uses the arithmetic-mean entropy normalization MI / ((H(gold) + H(predicted)) / 2). These partition-only metrics apply to PRIMARY_OUTPUT; candidate-relation rows show n/a.

Provenance

  • Authoritative source: docs/benchmarks/data/stemming-quality.csv
  • Source SHA-256: 5a93a6ab60e46489737cd649eb1ac48182114b9038f7f20195ab9d1c1fc0dd28
  • Evaluation command: ./gradlew stemmingQuality
  • Dictionary language: PL_PL
  • Processing modes: ALL_WORDS, LOWERCASE_GROUPS_ONLY
  • Stemmer versions and transitive artifacts: resolved by the repository's JMH Gradle configuration and gradle.lockfile
  • Radixor version, Git revision, generation date, JDK version, operating system, and dictionary revision: not recorded in the authoritative CSV
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