The%20Descent%20of%20Hierarchy,%20and%20Selection%20in%20Relational%20Semantics*

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The Descent of Hierarchy, and Selection in
RelationalSemantics

• Barbara Rosario, Marti Hearst, Charles Fillmore
• UC Berkeley

with apologies to Charles Darwin
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Noun Compounds (NCs)

• Technical text is rich with NCs
• Open-labeled long-term study of the
  subcutaneous sumatriptan efficacy and
  tolerability in acute migraine treatment.
• Any sequence of nouns that itself functions as a
  noun
• asthma hospitalizations
• health care personnel hand wash

3
NCs 3 computational tasks

• Identification
• Syntactic analysis (attachments)
• Baseline headache frequency
• Tension headache patient
• Our Goal Semantic analysis
• Headache treatment ? treatment for
  headache
• Corticosteroid treatment ? treatment that uses
  
  corticosteroid

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Descent of Hierarchy

• Idea
• Use the top levels of a lexical hierarchy to
  identify semantic relations
• Hypothesis
• A particular semantic relation holds between all
  2-word NCs that can be categorized by a lexical
  category pair.

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Outline

• Related work
• Linguistic motivation
• Lexical Hierarchy MeSH
• Labeling NC relations
• Method and results
• Discussion of ambiguity

6
Related work (Semantic analysis of NCs)

• Rule-based
• Finin (1980)
• Detailed AI analysis, hand-coded
• Vanderwende (1994)
• automatically extracts semantic information from
  an on-line dictionary, manipulates a set of
  handwritten rules. 13 classes,
  52 accuracy
• Probabilistic
• Lauer (1995)
• probabilistic model, 8 classes, 47 accuracy
• Lapata (2000)
• classifies nominalizations into subject/object.
  2 classes, 80 accuracy

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Related work (Semantic analysis of NCs)

• Lexical Hierarchy
• Barrett et al. (2001)
• WordNet, heuristics to classify a NC given the
  similarity to a known NC
• Rosario and Hearst (2001)
• MeSH, Neural Network. 18 classes, 60 accuracy
• Relations pre-defined

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Linguistic Motivation

• Semantics of the NCs head-modifier relationship
• Head noun has argument structure
• Meaning of the head noun determines what kinds of
  things can be done to it, what it is made of,
  what it is a part of

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Linguistic Motivation (cont.)

• Material Cutlery ? Made of
• steel knife, plastic fork, wooden spoon  
• Food Cutlery ? Used on
• meat knife, dessert spoon, salad fork 
• Profession Cutlery ? Used by
• chef's knife, butcher's knife

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Outline

• Related work
• Linguistic motivation
• Lexical Hierarchy MeSH
• Labeling NC relations
• Method and results
• Discussion of ambiguity

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The lexical Hierarchy MeSH

• Tree Structures
• 1. Anatomy A
• 2. Organisms B
• 3. Diseases C
• 4. Chemicals and Drugs D
• 5. Analytical, Diagnostic and Therapeutic
  Techniques and Equipment E
• 6. Psychiatry and Psychology F
• 7. Biological Sciences G
• 8. Physical Sciences H
• 9. Anthropology, Education, Sociology and
  Social Phenomena I
• 10. Technology and Food and Beverages J
• 11. Humanities K
• 12. Information Science L
• 13. Persons M
• 14. Health Care N
• 15. Geographic Locations Z

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The lexical Hierarchy MeSH

• 1. Anatomy A Body Regions A01
  
• 2. B
  Musculoskeletal System A02
• 3. C Digestive
  System A03
• 4. D Respiratory
  System A04
• 5. E Urogenital
  System A05
• 6. F
• 7. G
• 8. Physical Sciences H
• 9. I
• 10. J
• 11. K
• 12. L
• 13. M

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Descending the Hierarchy

• 1. Anatomy A Body Regions A01
  Abdomen A01.047
• 2. B
  Musculoskeletal System A02 Back
  A01.176
• 3. C Digestive
  System A03 Breast A01.236
• 4. D Respiratory
  System A04 Extremities A01.378
  
• 5. E Urogenital
  System A05 Head A01.456
• 6. F
  Neck
  A01.598
• 7. G
  .
• 8. Physical Sciences H
• 9. I
• 10. J
• 11. K
• 12. L
• 13. M

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Descending the Hierarchy

• 1. Anatomy A Body Regions A01
  Abdomen A01.047
• 2. B
  Musculoskeletal System A02 Back
  A01.176
• 3. C Digestive
  System A03 Breast A01.236
• 4. D Respiratory
  System A04 Extremities A01.378
  
• 5. E Urogenital
  System A05 Head A01.456
• 6. F
  Neck
  A01.598
• 7. G
  .
• 8. Physical Sciences H Electronics
• 9. I
  Astronomy
• 10. J
  Nature
• 11. K
  Time
• 12. L
  Weights and Measures
• 13. M .

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Descending the Hierarchy

• 1. Anatomy A Body Regions A01
  Abdomen A01.047
• 2. B
  Musculoskeletal System A02 Back
  A01.176
• 3. C Digestive
  System A03 Breast A01.236
• 4. D Respiratory
  System A04 Extremities A01.378
  
• 5. E Urogenital
  System A05 Head A01.456
• 6. F
  Neck
  A01.598
• 7. G
  .
• 8. Physical Sciences H Electronics
  Amplifiers
• 9. I
  Astronomy Electronics, Medical
• 10. J
  Nature Transducers
• 11. K
  Time
• 12. L
  Weights and Measures
• 13. M .

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Descending the Hierarchy

• 1. Anatomy A Body Regions A01
  Abdomen A01.047
• 2. B
  Musculoskeletal System A02 Back
  A01.176
• 3. C Digestive
  System A03 Breast A01.236
• 4. D Respiratory
  System A04 Extremities A01.378
  
• 5. E Urogenital
  System A05 Head A01.456
• 6. F
  Neck
  A01.598
• 7. G
  .
• 8. Physical Sciences H Electronics
  Amplifiers
• 9. I
  Astronomy Electronics, Medical
• 10. J
  Nature Transducers
• 11. K
  Time
• 12. L
  Weights and Measures Calibration
• 13. M .
  Metric
  System
• 
  
  Reference Standard

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Descending the Hierarchy

• 1. Anatomy A Body Regions A01
  Abdomen A01.047
• 2. B
  Musculoskeletal System A02 Back
  A01.176
• 3. C Digestive
  System A03 Breast A01.236
• 4. D Respiratory
  System A04 Extremities A01.378
  
• 5. E Urogenital
  System A05 Head A01.456
• 6. F
  Neck
  A01.598
• 7. G
  .
• 8. Physical Sciences H Electronics
  Amplifiers
• 9. I
  Astronomy Electronics, Medical
• 10. J
  Nature Transducers
• 11. K
  Time
• 12. L
  Weights and Measures Calibration
• 13. M .
  Metric
  System
• 
  
  Reference Standard

Homogeneous
Heterogeneous
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Mapping Nouns to MeSH Concepts

• headache recurrence
• C23.888.592.612.441 C23.550.291.937
• headache pain
• C23.888.592.612.441 G11.561.796.444
• breast cancer cells
• A01.236 C04 A11

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Levels of Description

• headache pain
• Level 0 C.23 G.11
• Level 1 C23.888 G11.561
• Level 1 C23.888.592 G11.561.796
• Original C23.888.592.612.441 G11.561.796.444

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Outline

• Related work
• Linguistic motivation
• Lexical Hierarchy MeSH
• Labeling NC relations
• Method and results
• Discussion of ambiguity

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Descent of Hierarchy

• Idea
• Words falling in homogeneous MeSH subhierarchies
  behave similarly with respect to relation
  assignment
• Hypothesis
• A particular semantic relation holds between all
  2-word NCs that can be categorized by a MeSH
  category pairs

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Grouping the NCs

• CP A02 C04 (Musculoskeletal System, Neoplasms)
• skull tumors, bone cysts, bone metastases, skull
  osteosarcoma
• CP C04 M01 (Neoplasms, Person)
• leukemia survivor, lymphoma patients, cancer
  physician, cancer nurses

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Distribution of Category Pairs
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Collection

• 70,000 NCs extracted from titles and abstracts
  of Medline
• 2,627 CPs at level 0 (with at least 10 unique
  NCs)
• We analyzed
• 250 CPs with Anatomy (A)
• 21 CPs with Natural Science (H01)
• 3 CPs with Neoplasm (C04)
• This represents 10 of total CPs and 20 of total
  NCs

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Classification Method

• For each CP
• Divide its NCs into training-testing sets
• Training inspect NCs by hand
• Start from level 0 0
• While NCs are not all similar
• descend one level of the hierarchy
• Repeat until all NCs for that CP are similar

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Using the CPs for classification

• CP A02 C04 (Musculoskeletal System, Neoplasms)
• skull tumors, bone cysts, bone metastases, skull
  osteosarcoma

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Using the CPs for classification

• CP A02 C04 (Musculoskeletal System, Neoplasms)
• skull tumors, bone cysts, bone metastases, skull
  osteosarcoma
• Similar NCs
• All NCs under the CP A02 C04 have the same
  semantic relationship
• Location of disease? Disease in Anatomy?

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Using the CPs for classification

• CP A02 C04 (Musculoskeletal System, Neoplasms)
• skull tumors, bone cysts, bone metastases, skull
  osteosarcoma
• Similar NCs
• All NCs under the CP A02 C04 have the same
  semantic relationship
• Location of disease? Disease in Anatomy?
• Add CP A02 C04 to the list of classification
  decisions

Classification decisions A02 C04
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Using the CPs for classification

• CP B06 B06 (Plants, Plants)
• eucalyptus trees, apple fruits, rice grains,
  potato plants

Classification decisions A02 C04
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Using the CPs for classification

• CP B06 B06 (Plants, Plants)
• eucalyptus trees, apple fruits, rice grains,
  potato plants
• Similar
• Same relationship
• Add CP B06 B06

Classification decisions A02 C04 B06 B06
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Using the CPs for classification

• CP C04 M01 (Neoplasms, Person)
• leukemia survivor, lymphoma patients, cancer
  physician, cancer nurses
• Person afflicted by Disease? Person who treat
  Disease?
• Too different!
• Second noun needs to be more specific Descend
  one level for the second noun Person

Classification decisions A02 C04 B06 B06
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Using the CPs for classification

• CP C04 M01 (Neoplasm, Person)
• leukemia survivor, lymphoma patients, cancer
  physician, cancer nurses
• ? Too different!
• CP C04 M01.643 (Neoplasms, Patients)
• leukemia survivor, lymphoma patients
• Person afflicted by Disease
• CP C04 M01.526 (Neoplasms, Occupational Groups)
• cancer physician, cancer nurses
• Person who treat Disease
• OK

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Classification Decisions

• A02 C04
• B06 B06
• C04 M01
• C04 M01.643
• C04 M01.526
• A01 H01
• A01 H01.770
• A01 H01.671
• A01 H01.671.538
• A01 H01.671.868
• A01 M01
• A01 M01.643
• A01 M01.526
• A01 M01.898

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Classification Decisions Relations (future
work)

• A02 C04 ? Location of Disease
• B06 B06 ? Kind of Plants
• C04 M01
• C04 M01.643 ? Person afflicted by Disease
• C04 M01.526 ? Person who treats Disease
• A01 H01
• A01 H01.770
• A01 H01.671
• A01 H01.671.538
• A01 H01.671.868
• A01 M01
• A01 M01.643
• A01 M01.526
• A01 M01.898

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Classification Decisions Relations (future
work)

• A02 C04 ? Location of Disease
• B06 B06 ? Kind of Plants
• C04 M01
• C04 M01.643 ? Person afflicted by Disease
• C04 M01.526 ? Person who treats Disease
• A01 H01
• A01 H01.770
• A01 H01.671
• A01 H01.671.538
• A01 H01.671.868
• A01 M01
• A01 M01.643 ? Person afflicted by Disease
• A01 M01.526
• A01 M01.898

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Classification Decision Levels

• Anatomy 250 CPs
• 187 (75) remain first level
• 56 (22) descend one level
• 7 (3) descend two levels
• Natural Science (H01) 21 CPs
• 1 (4) remain first level
• 8 (39) descend one level
• 12 (57) descend two levels
• Neoplasms (C04) 3 CPs
• 3 (100) descend one level

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Evaluation

• Test the decisions on testing set
• Count how many NCs that fall in the groups
  defined in the classification decisions are
  similar to each other
• Accuracy
• Anatomy 91 accurate
• Natural Science 79
• Neoplasm 100
• Total Accuracy 90.8
• Generalization our 415 classification decisions
  cover 46,000 possible CP pairs

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Outline

• Related work
• Linguistic motivation
• Lexical Hierarchy MeSH
• Labeling NC relations
• Method and results
• Discussion of ambiguity

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Ambiguity Two Types

• Lexical ambiguity
• mortality
• state of being mortal
• death rate
• Relationship ambiguity
• bacteria mortality
• death of bacteria
• death caused by bacteria

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Lexical Ambiguity vs. Multiple MeSH Senses

• Lexical ambiguity different from multiple MeSH
  senses
• Ex Mortality has 4 senses
• Public Health (G) ? Data Collection ? Vital
  Statistics  ? Mortality
• Investigative Techniques (E) ? Data Collection ?
  Vital Statistics  ? Mortality
• Information Science (L) ? Data Collection ? Vital
  Statistics  ? Mortality
• Population Characteristics (N) ? Demography ?
  Vital Statistics  ? Mortality
• On average, there are 1.5 MeSH senses per word
  for the nouns in our collection

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Four Cases
Single MeSH senses
Multiple MeSH senses
Only one possible relationship abdomen
radiography, aciclovir treatment
Only one possible relationship alcoholism
treatment
Multiple relationships hospital databases,
education efforts, kidney metabolism
Multiple relationships bacteria mortality
Ambiguity of relationship
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Four Cases
Single MeSH senses
Multiple MeSH senses
Only one possible relationship abdomen
radiography, aciclovir treatment
Only one possible relationship alcoholism
treatment
Multiple relationships bacteria mortality
Multiple relationships hospital databases,
education efforts, kidney metabolism
Most problematic cases
Ambiguity of relationship
but rare!
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Conclusions

• Very simple method for assigning semantic
  relations to two-word technical NCs
• 90.8 accuracy
• Grouping the NCs with respect to their semantic
  descriptors
• Lexical resource (MeSH) useful for this task
• Use the upper levels of the lexical hierarchy for
  an accurate classification, reducing therefore
  the space of the problem

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Future work

• Analyze full spectrum of hierarchy
• NCs with gt 2 terms
• growth hormone deficiency
• Other syntactic structures
• Non-biomedical words
• Other ontologies (e.g.,WordNet)?

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And given enough data

• skull character
• jaw depression
• nose resuscitation
• cadaver motion

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Thanks!For more informationhttp//bailando.
sims.berkeley.edu/lindi/