Relations between multiple annotations: Representation, Inferences, Context Specification, and Unifi

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Relations between multiple annotations
Representation, Inferences, Context
Specification, and Unification

• Andreas Witt
• Dieter Metzing
• Jens Pönninghaus
• Daniela Goecke

www.text-technology.de
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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Project description

• The Project secondary information structuring and
  comparative discourse analysis (Sekimo) is part
  of the DFG-Forschergruppe 437 Text-technological
  modelling of information
• Within this Project a corpus is annotated on
  different (linguistic) levels
• Aim of the project Inferring, Describing, and
  Modelling relations between these levels

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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Standard Methodology

• A corpus is annotated according to a given tag
  set
• The tag set is defined in a document grammar
  (e.g. the TEI-DTD)
• In general, different tag sets exist for
  annotating different kinds of documents (e.g.
  poems, encyclopedia) or different kinds of
  information (e.g. linguistic information)
• In particular, a linguistic annotation can depend
  on
• theoretical assumptions
• constituent structure,
• functional structure, or
• a (more) specific theory
• the language
• research questions

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Problems of the standard methodology

• Levels of description are neglected
• or
• Different levels of annotation are mixed up

Difficulties

• Multiple hierarchies within one document

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General Solutions (c.f. TEI-Guidelines)

• concur an optional feature of SGML (not
  available in XML) which allows multiple
  hierarchies to be marked up concurrently in the
  same document
• milestone elements empty elements which mark the
  boundaries between elements in a non-nesting
  structure
• fragmentation of an item the division of what
  logically is a single element into two or more
  parts, each of which nests properly within its
  context
• virtual joins the recreation of a virtual
  element from fragments of text, (requires a
  separate interpretation)
• redundant encoding of information in multiple
  forms

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Multiple hierarchies and language data

• Hypertext linking techniques are used for
  connecting multiple layers of annotation, e.g.
• Within the EU-Project NITE an annotation format
  has been developed which allows for specifying
  links between separate annotation layers
• The annotation graphs (AGs) format uses a
  (possibly abstract) timeline as linking-layer
• Modified versions of the AGs are applied by
• the TASX-Annotator
• the EXMARaLDA-Project

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Alternative Methodology

• XML-based multi-layer annotation
• Technically, each layer becomes a separate and
  independent XML-document
• The same text is annotated several times
• Advantages
• seems to be the only way to annotate multiple
  hierarchies without workarounds
• each document instance uses its own DTD (or
  Schema), i.e. annotation formats are not mixed up
  
• at any time a new annotation can be produced
• transformation tools to the NITE and the
  TASX-format exist (Masters Thesis by Jan F. Maas)

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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Layer vs. Level

• We distinguish annotation level vs. annotation
  layer
• Annotation level refers to an abstract level of
  analysis
• Annotation layer refers to the realisation of an
  annotation in e.g. XML
• Examples of annotation levels morphology in a
  linguistic grammar, text structure (sections,
  paragraphs,...), layout (lines and pages),
  thematic structure, rhetorical structure
• Sometimes one layer contains several levels (e.g.
  HTML), but a level can also be distributed over
  several layers

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Annotation Process

• Given
• the textual representation of language material
  (text)
• the text is regarded as primary data
• For each annotation layer the primary data is
  copied
• The (copy of the) primary text is annotated
  according to a schema (e.g. a DTD)
• Annotation can be prepared
• in any XML-Editor (e.g. XMetaL, XML-Spy,
  psgml-emacs)
• special purpose annotation tool

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Sample annotation with a web-based, special
purpose annotation tool This tool is used only
for flat xml-structures, i.e. xml-annotations
with non-nested elements
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ExampleXML-Annotation with the emacs
editor(useable for deep and flat annotations)
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Multi-layer-annotation tool (master's thesis by
Stefan Michel work in progress)
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Multiple Annotations

• Drawbacks
• redundant
• the separate documents are independent (i.e. not
  connected)
• But
• since the documents contain exactly the same
  text, the text can function as the link
• Solution
• a common representation format for all separate
  XML-documents

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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Prolog-Representation

• The Prolog-representation is based on work by
  Renear, Huitfeld, Dubin and Sperberg-McQueen
• Original representation for an XML-Elementnode/2,
  i.e. the predicate node has two arguments
• the position in the document tree
• a value, e.g. element(corpus)
• Extension node/2 is replaced by node/5
• The 3 new arguments
• annotation layer
• startingpoint of the annotated text
• end-point of the annotated text

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Conversion from XML to Prolog (xml2prolog)

• Implemented in Python
• Input 1 or more XML-Documents
• Result Collection of Prolog facts
• Example
• the element ltRootgt is represented as the fact
• node(AnnotationLayer, 0, 42332, 1,
  element(Root)).
• the attribute attval of the Element ltRootgt is
  represented as the fact
• attr(AnnotationLayer, 0, 42332, 1, 'att',
  'val').

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xml2prolog.py

• Some options for the transformation process
• compare the primary data of the XML files are
  compared, if the primary data is not identical,
  the first difference is shown
• pcdata/pcdatanodes character data can be
  included
• aggressive whitespace is added or removed
  anywhere in document if whitespace is the reason
  for differences of the primary data
• filter some elements in some files should be
  filtered (including their textual content), e.g.
  ltscriptgt within HTML-documents

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Example
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Example (Collection of Prolog-Facts)
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Example (Collection of Prolog-Facts)
annotation layer start- and endpoint nodes in
DOM-tree element names attribute-value-pair data-c
ontents
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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Relations between annotation Layers

• Relations are inferred automatically
• Special Prolog predicates have been implemented,
  for
• compare the annotation layers
• Example (Identity)
• ltwgttreelt/wgt
• ltmgttreelt/mgt
• ltsyllgttreelt/syllgt

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Relations between Annotations
Vgl. Durusau Brook O'Donnell (2002) und Durand
(1999)
1. ltagt....................lt/agt
ltbgt......lt/bgt 2. ltagt.................
...lt/agt
ltbgt.........lt/bgt 3. ltagt....................lt/agt
ltbgt.....................lt/bgt 4.
ltagt....................lt/agt
ltbgt................................lt/bgt 5.
ltagt....................lt/agt ltbgt.................
.........................lt/bgt 6.
ltagt....................lt/agt
ltbgt......lt/bgt 7. ltagt....................lt/agt
ltbgt....................lt/bgt 8.
ltagt....................lt/agt ltbgt.................
..............lt/bgt etc.
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Relations between annotation layers
Visualisation
Relation
identity
independence
inclusion
start point identity
end point identity
end point is starting point
overlap
range of element a
range of element b
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Comparison of annotation layers

• We distinguish two kinds of relations between
• elementsrelations between single instances of an
  element (relations)
• relations between all occurrences of instances an
  element (meta-relations)
• Prolog programs have been developed to infer both
  kinds of relations

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Prolog Implementation

• Aims
• statistics on annotation layers
• relations between occurrences of elements
• meta-relations

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Example deep annotation (HPSG)
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Statistics of the annotation according to HPSG
?- get_statistics. Please enter layer name or
type "q" to exit, "h" for help
hpsg. Statistics for hpsg Number of Nodes 14,
Number of different Elements 5 Number of
Attributes 1, Number of different A/V-pairs
4 ------------------------------------------ Diffe
rent elements and their occurrences
hpsg 1 nodesAndLabels
3 nonannotated-text 4 phrase
2 punctuation
4 ------------------------------------------ Attri
bute occurrences different
values type 5 4 For
information on occurrences of Attribute-Value-Pair
s enter Attribute name or type q to quit.
type. ( edgeCOMP,1 ) , ( edgeHD,2 ) , ( np,1 ) ,
( np-no,1 )
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Relations between occurrences of elements

• Query How often does a certain relation between
  elements hold?
• chk_relation(Relation,Element1,Layer1,Element2,La
  yer2,L).
• Relation a relation between elements (e.g.
  identity, overlap, or
• endA_is_starting_pointB)
• Element1 element name of annotation Layer1
• Element2 element name of annotation Layer2
• L result-list
• It is also possible to infer examples and
  counter-examples of a certain relation

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ExampleRelations between elements of the HPSG
Annotation and the elements of a
dialogue-annotation
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Ex. Relations between HPSG-phrases and X
?- chk_relation(Relation,phrase,hpsg,X,dialogue,L)
. Relation identity X _G160 L
Relation included_B_in_A X _G160 L
Relation included_A_in_B X _G160 L
phrase, dialogue, 2, phrase, 2, dialogue,
1 ... Relation overlap_A X _G160 L
Yes
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Meta-relations

• If a certain relation holds for all instances of
  an element we defined meta-relation
• identity At every occurrence of an element A in
  Layer1 an element B in Layer2 exists which spans
  the same range of characters
• inclusion
• at every occurrence of an element A in Layer1 an
  element B in Layer2 exists which is included or
  is identical
• the meta relation identity does not hold
• overlap At every occurrence of an element A in
  Layer1 an element B in Layer2 exists which
  overlaps with A
• mixed no meta-relations exist

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Meta-relations (cntd.)

• identity - For all occurrences, the following
  configuration can found
• ltagt....................lt/agtltbgt..................
  ..lt/bgt
• inclusion - For all occurrences, one of the
  following configurations can be found
• ltagt....................lt/agt
  ltbgt................................lt/bgt
• ltagt....................lt/agt ltbgt...............
  ...........................lt/bgt
• ltagt....................lt/agtlt
  bgt.......................................lt/bgt
• ltagt....................lt/agtltbgt..................
  ..lt/bgt
• overlap - For all occurrences, the following
  configuration can found
• ltagt....................lt/agt
  ltbgt....................lt/bgt

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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Context specification 1 Motivation

• Often, general Meta-relations do not hold
• In these cases, the elements can be classified
  according to structural properties within their
  layer
• This allows to construct specific Meta-relations
• A format to express the structural properties
  called Context Specification Document (CSD) has
  been developed

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Context specification 2 Realization

• Subclassification of element nodes via tree
  walking automata (TWA)
• Underlying path-language for the construction of
  TWA Caterpillar-Expressions (cf.
  Brüggemann-Klein and Wood, 2000)
• moves up, right, left, firstChild, lastChild
• tests isFirst, isLast, isLeaf, isRoot
• test for element names
• Kleene-star operator

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Sample application
NP
COMP
HD
NF
NP.NO
COMP
HD
VN
PGen
k e N
shucchou
no
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Context specification 3 Subclassification
NP
COMP
HD
NF
NP.NO
Relation holds for all Comp Elements
COMP
HD
VN
PGen
Relation holds only for a subset
k e N
shucchou
no
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Contents

• Project description
• Approaches to Multiple Annotations
• multiple Levels
• multiple Layers
• Representation
• Inferences
• Context Specification
• Unification

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Unification of annotation layers I

• Two document layers can be merged
• This process has also been implemented in Prolog
• The predicate (semt) receives four arguments.
• layer1 (to be unified)
• layer2 (to be unified)
• list of elements which should be deleted in the
  process of unification
• The result of the merger (again a collection of
  Prolog facts) is written to a new file specified
  in the fourth argument
• The new database contains a copy of all layers in
  the input database plus the result layer
• In case the unification results to a layer where
  the elements would not be properly nested, a
  second result layer (a difference list) is
  created.

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Unification of annotation layers II

• The result database is re-converted to XML using
  a python program
• If no difference list exists, the result of the
  merging of two layers can be linearised as an XML
  document straightforwardly
• In case the result fact base contains a
  difference list, two different linearisations can
  be generated.
• the default processing uses milestone elements to
  mark the borders of incompatible elements.
• alternatively, the technique of fragmentation of
  elements can be invoked.

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Architecture
Inference/ Query
via Python
XML-docu-ments
Generation of XML from the fact
base Unification of annotation levels
via Python
External information
XML-docu-ments
Rules
Rules
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Contents

• Project description
• Approaches to Multiple Annotations
• Representation
• Inferences
• Context Specification
• Unification

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Relations between multiple annotations
Representation, Inferences, Context
Specification, and Unification

• Andreas Witt
• Dieter Metzing
• Jens Pönninghaus
• Daniela Goecke

www.text-technology.de