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Computer science for BA > week 2/3 > Flashcards

week 2/3 Flashcards

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1
Q

RDF Graph =

A

set of triples

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2
Q

a triple:

A

subject, predicate, object

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3
Q

RDF graph representation

A

node and directed arc (labeled) diagram

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4
Q

semantic web is based on…

A

triples

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5
Q

… are the cornerstone of the semantic web

A

ontologies

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6
Q

components of ontologies

A

classes, relations, axioms, instances

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7
Q

OWL =

A

ontology web language

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8
Q

One of specializations of OWL is

A

RDF/XML

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9
Q

owl: =

A

comes from owl name space and is used to define types in ontology

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10
Q

rdf:ID=”” where ID is the

A

class

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11
Q

symbol in serialized owl means

A

refer to this resource somewhere else in document

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12
Q

rdfs: domain means

A

allowed to use property only on certain instances

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13
Q

kb: in serialized owl means

A

knowledge base, defined by user

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14
Q

hermes framework input

A

news items from rss feesds, domain ontology linked to a semantic lexicon, user query

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15
Q

hermes framework outpu

A

news items as answer to the user query

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16
Q

4 phases HF

A
  1. News classification: relate news to ontology concepts
  2. Knowledge Based Updating: update knowledge base with info
  3. News querying: allow user to express concepts of interest and the temporal constraints
  4. Result presentation: present the news items that match user’s query
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17
Q

3 types of users domain ontology

A

casual user, domain expert, knowledge engineer

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18
Q

ontology development

A

incremental middle-out approach, anchor concepts to their corresponding wordnet synsets, validated using the ontoclean methodology

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19
Q

preprocessing of news

A

filter out duplicates news (heuristic based on title)

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20
Q

multiple lexical representations for same concept:

A

ontology synonyms and semantic lexicon synonyms

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21
Q

concepts w/o subclasses or instances:

A

semantic lexicon hypernyms

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22
Q

a longer match in news classification subsedes ..

A

a shorter match

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23
Q

WSD:

A

interconnection based on word context and a semantic lexicon

24
Q

synset:

A

set of synonyms

25
Q

sense:

A

word with specific meaning

26
Q

synset relations:

A

hypo/hypernyms, syno/antonyms, holo/meronyms

27
Q

KBU, detect …

A

events in news items

28
Q

events in KBU have associated…

A

lexico sem patterns for their detection and actions for KBU

29
Q

KBU:variables are used to..

A

link extracted info with update information

30
Q

KBU: events are stored in…

A

ontology

31
Q

query formulation. Present domain knowledfe as…

A

directed labeled multigraph

32
Q

query formulation. User selects…

A

direct concepts of interest in conceptual graph

33
Q

QF: user is able to add to its selection

A

indirect concepts of interest

34
Q

news is time

A

stampled

35
Q

query execution:

A

generate query in semantic query language and execute the semantic query

36
Q

sort news items based on..

A

their relevance degree to the query

37
Q

results presentation, per each news item show a…

A

summary

38
Q

Hermes news portal HNP is an implementation of..

A

the hermes framework

39
Q

precision=

A

concepts correctly identified in news items/# of concepts identified in news items

40
Q

recall=

A

concepts correctly identified in news items/ # of concepts that should have been identified in the news items

41
Q

Hermes framework presents ..

A

news items that match user interests

42
Q

hermes cornerstone:

A

domain ontology anchored in a semantic lexicon

43
Q

HNP based on

A

wordnet semantic lexicon, owl ontology,, sparql queries etc.

44
Q

event =

A

rela between 2 entities in text

45
Q

application of event extraction in..

A

news classification and KBU

46
Q

event extraction languages:

A

lexico syntatic(uses lexical and syntatic info to extract events), lexico semantic (also uses semantic info from domain ontology)

47
Q

why hermes phases have to happen in certain order?

A

in order to update knowledge base, it’s important to know which concepts from the knowledge base have been already found in the news. In order to query the news, its important to have the most up to date knowledge base view on the real world. As news querying uses a boolean query, in the results representation its needed to rank the query output based on the query generalized disjuncitve semantics and present the results in a user visually appealing manner

48
Q

3 owl features needed for modelling the domain ontology

A 
cardinality restrictions (hasceo has cardinality 1)
property symmetry (competitor is a symmetric property)
property inverse (inverse of hasceo is isceoooof)
49
Q

why hermes uses a beta is 0.3 in F_beta

A

in hermes rule learning its given priority to precision over recall when learning 1 rule, as the group of learned rules per event will ensure a high recall

50
Q

difference lexico syntatic and lexico semantic pattern language to info extraction?

A

lexico sem pattern utilizes concepts from domain ontology which makes it easier to build and maintain patterns due to their increased expressivity and conciseness compared to their lexico syntactic counterparts

51
Q

performance of lexico syntactic and lexico semantic rules is evaluated based on..

A

rule creation times, precision, recall and F1 measure

52
Q

f1 measure =

A

harmonic mean within precision and recall

53
Q

groups of rules extract…

A

specific events

54
Q

rule learning using genetic programming termination criteria

A

rule: fixed number of its (keep best rule)

rule group: max number of its didnt improve rule group

55
Q

fitness of a rule has values

A

alpha and beta

56
Q

by beta smaller than 1 we give more importance to..

A

precision

Computer science for BA (3 decks)

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