The document discusses linguistic resources created for improving access to 16th century German texts. It describes how the IMPACT project adapted resources like lexicons to account for the differences between historical and modern German. A groundtruth corpus spanning 1500-1950 was created, as well as a hypothetical lexicon of rule-based variants and a manually verified lexicon to map historical words to their modern equivalents. These resources were able to cover 30% of 16th century vocabulary and improve optical character recognition.

1. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Special resources to access 16th century German
Ludwig-Maximilians-Universität München
Annette Gotscharek
15. 10. 2011, IMPACT Conference

2. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Special resources to access 16th century German
“access”?
 OCR:
Role of the lexicon: defines the set of valid words.
... Geist
Geister
Teile
gemütlich …
 Information Retrieval (IR):
Role of the lexicon: meaningful expansion of the user query to increase recall.
... Geist  Geister, Geiste, Geistern
Teil  Teile, Teils, Teilen
gemütlich  gemütlicher, gemütlichste ...
15. 10. 2011, IMPACT Conference 2

3. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Special resources to access 16th century German
 In IMPACT, we worked on documents from 1500-1950, but 16th century is special:
– Language period: Early New High German (1350-1650)
– Oldest and therefore most challenging period of printed books
– Large library holdings from 16th century at our partner library BSB
 linguistic features of historical language on word-level
Historic  modern English
– Historical spelling variation: geyſte Geiste spirit
– Historical morphology: er frug  er fragte he asked
– Obsolete vocabulary: mirackel Wunder (?) miracle
– Obsolete character set: aͤ ä…
 Need adapted linguistic resources
15. 10. 2011, IMPACT Conference 3

4. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Adapted linguistic resources: structure
 OCR:
... Geist
Geister
Teile
gemütlich …
 Information Retrieval (IR):
... Geist  Geister, Geiste, Geistern
Teil  Teile, Teils, Teilen
gemütlich  gemütlicher, gemütlichste ...
15. 10. 2011, IMPACT Conference 4

5. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Adapted linguistic resources: structure
 OCR:
... Geist Geyst
Geister Geyster
Teile Theile
gemütlich gemüthlich …
 Information Retrieval (IR):
... Geist  Geister, Geiste, Geistern Geyster, Geyste, Geystern
Teil  Teile, Teils, Teilen Theile, Theils, Theilen
gemütlich  gemütlicher, gemütlichste gemüthlicher, gemüthlichste...
15. 10. 2011, IMPACT Conference 5

6. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Linguistic Resources for Historical Texts
 Diachronic Groundtruth Corpus (1500-1950)
 Hypothetical lexicon for rule based variants
 Manually verified lexicon
15. 10. 2011, IMPACT Conference 6

7. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Linguistic Resources for Historical Texts
 Diachronic Groundtruth Corpus (1500-1950)
 Hypothetical lexicon for rule based variants
 Manually verified lexicon
15. 10. 2011, IMPACT Conference 7

8. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Diachronic Groundtruth Corpus (1500-1950)
 Collection of groundtruth material from different sources in the web and non-public
electronic corpora (Institut für Deutsche Sprache Mannheim)
 Large gap especially in 16th / 17th century:
 with BSB: preparation of additional corpus from BSB documents:
– Random selection of 100 works from digitized images of 16th and 17th century
– Mostly related to theology
– Latin texts excluded, no poems etc.
– Keyed by a service provider
– 1766 pages with ~ 858,000 tokens groundtruth material
15. 10. 2011, IMPACT Conference 8

9. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Diachronic Groundtruth Corpus (1500-1950)
 Gains of tokens by the extension of the corpus:
 Complete corpus contains ~ 3,380,000 tokens in 500 texts from 4 centuries
 basis for different analyses and lexicon building
15. 10. 2011, IMPACT Conference 9

10. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Coverage on Diachronic Corpus: modern
Types (%) 1500- 1550- 1600- 1650- 1700- 1750- 1800- 1850- 1900-
– 1549 1599 1649 1699 1749 1799 1849 1899 1949
Modern simple 15.3 28.8 29.2 31.5 38.1 52.0 54.7 48.0 60.1
words
Modern 5.1 6.1 6.9 8.6 7.13 15.5 20.6 28.1 27.8
compounds
 Less than 45% of the vocabulary is covered by modern resources before 1750.
 16th century: only 15% - 29% modern simple words, modern closed compounds
are hardly relevant.
15. 10. 2011, IMPACT Conference 10

11. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Linguistic Resources for Historical Texts
 Diachronic Groundtruth Corpus (1500-1950)
 Hypothetical lexicon for rule based variants
 Manually verified lexicon
15. 10. 2011, IMPACT Conference 11

12. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Hypothetical lexicon for rule based variants
 Systematic substitution rules (patterns) describe the difference
between modern and historical spelling:
t th,ei ey
(modern) teil theyl (historic)
 Based on the modern lexicon and the 140 manually collected
patterns, the set of all potential rule based historical variants can be
computed automatically (“hypothetical lexicon”).
15. 10. 2011, IMPACT Conference 12

13. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Hypothetical lexicon for rule based variants
hypothetical
lexicon
…
Esel Teil
… Esel Teill
Teil Esell Teyl
…
… Esehl e →eh
Teyll
Esehll ei →ey
Tehill
Eßel s →ß
Theil
modern Eßell l→ll
…
Eßehll t →th
lexicon …
…
pattern set
15. 10. 2011, IMPACT Conference 13

14. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Hypothetical lexicon for rule based variants
 Automatic mapping from rule based historical variants to their equivalent in
the modern vocabulary is possible:
historic modern
Geyst = Geist + (ei  ey)
Theile = Teile + (t th)
 By far not all historical variants can be described by simple replacement rules:
historic modern
frug = fragte + ?
Mirackel = ?+?
15. 10. 2011, IMPACT Conference 14

15. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Coverage on Diachronic Corpus: hypothetic
Types (%) 1500- 1550- 1600- 1650- 1700- 1750- 1800- 1850- 1900-
1549 1599 1649 1699 1749 1799 1849 1899 1949
Modern simple 15.3 28.8 29.2 31.5 38.1 52.0 54.7 48.0 60.1
words
Modern 5.1 6.1 6.9 8.6 7.13 15.5 20.6 28.1 27.8
compounds
Hypothetic 29.5 29.8 27.9 26.0 21.9 14.3 8.1 7.7 2.0
 16th century: 30% of the vocabulary are covered by the lexicon of rule based
variants
 Applied as OCR-Lexicon via the IMPACT Abbyy External Dictionary Interface:
improvement of recognition rate (published 2009)
15. 10. 2011, IMPACT Conference 15

16. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Coverage on Diachronic Corpus: missing
Types (%) 1500- 1550- 1600- 1650- 1700- 1750- 1800- 1850- 1900-
1549 1599 1649 1699 1749 1799 1849 1899 1949
Modern simple 15.3 28.8 29.2 31.5 38.1 52.0 54.7 48.0 60.1
words
Modern 5.1 6.1 6.9 8.6 7.13 15.5 20.6 28.1 27.8
compounds
Hypothetic 29.5 29.8 27.9 26.0 21.9 14.3 8.1 7.7 2.0
Missing 45.9 28.7 29.7 26.0 23.5 15.1 13.9 13.5 8.1
 Especially in the 16th century: Up to 46% “difficult” vocabulary.
 manually verified lexicon necessary!
15. 10. 2011, IMPACT Conference 16

17. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Linguistic Resources for Historical Texts
 Diachronic Groundtruth Corpus (1500-1950)
 Hypothetical lexicon for rule based variants
 Manually verified lexicon
15. 10. 2011, IMPACT Conference 17

18. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Manually verified IR-lexicon: Structure
One entry contains:
– Historical word form from the corpus
– Corresponding modern word form
– Patterns if applicable
– Corresponding modern lemma
– At least one occurrence in the corpus as a attestation for the reading
 Manual assignment of modern word form and lemma
 Explicit handling of not rule based variants
15. 10. 2011, IMPACT Conference 18

19. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Manually verified IR-lexicon: Compilation
 Web-based, collaborative user interface
 User support:
– For rule based variants: Suggestion of the corresponding modern word
form by the hypothetic lexicon
– Suggestion of all possible lemmas for the modern word form by a large
modern lexicon (CISLEX)
– Concordance list of the historical variant
15. 10. 2011, IMPACT Conference 19

20. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Manually verified IR-lexicon: Status
 41,600 entries have been created for 24,800 historical word forms
from the diachronic corpus, 72,100 attestations were annotated.
 IMPACT-Partner in Slovenia und Bulgaria create corresponding
lexica with an adapted version of the tool.
15. 10. 2011, IMPACT Conference 20

21. IMPACT is supported by the European Community under the FP7 ICT Work Programme. The project is coordinated by the National Library of the Netherlands.
Thank you.
15. 10. 2011, IMPACT Conference 21