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Introduction to AI (3/3) > Knowledge Representation > Flashcards

Knowledge Representation Flashcards

1
Q

What are the major phases of Watson?

A
  1. Query Processing
  2. Answer Candidate Generation
  3. Evidence Retrieval & Scoring
  4. Evidence Ranking
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2
Q

Answering questions requires only keyword evidence.

A

False.

Keyword matching may be weak relative to other types of evidence.

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3
Q

To answer complex questions, it is not sufficient to simply match text in queries to text in documents. What kinds of knowledge are required?

A

Temporal, biographical, geographical and linguistic (e.g., different meanings of the word ‘arrival’)

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4
Q

Aristotle, by thinking of automation, laid the foundations for logic

A

True. He observed that such patterns work for all types of objects.

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5
Q

What does propositional logic consist of?

A
  • Propositions (TRUE, FALSE)
  • Logical operators (AND, OR, NOT, IMPLIES)
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6
Q

What does first order logic add to propositional logic?

A
  • Constants (represent objects, e.g. Frodo)
  • Relations (represent relations, e.g. married)
  • Quantifiers (represent existential or universal states)
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7
Q

Prolog is a powerful logic-based programming language.

A

True. Prolog means Programming and Logic.

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8
Q

What is Datalog?

A

A simple version of Prolog. It adds automated reasoning to database queries.

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9
Q

Who performed the first automated theorem proving?

A

J.A. Robinson, in 1965

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10
Q

When did Kowalski and Colmerauer make the first attempts for programming in logic?

A

In the 1950s.

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11
Q

A predicate denotes a relation between two objects.

A

True.

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12
Q

In Logical Notation, what do Constants and Variables represent?

A
  • Constants: some objects
  • Variables: unknown objects
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13
Q

In Prolog, we can’t describe relations.

A

False.

We can denote the relation “pam is a parent of bob” in a statement parent(pam,bob)

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14
Q

In Prolog, we can query relations only unidirectionally.

A

False. We can query in both directions:
?- parent(X,liz) or
?- parent(liz,X)

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15
Q

In Prolog, what is a Conjunction?

A

When we connect two conditions (literals) with the logical operator (AND), denoted by a comma.

happy(john), sunny_day both must be true

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16
Q

In Prolog, different variable names have to be different objects.

A

False.

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17
Q

In Prolog, how do we define a new relation?

A

We assign a new name to a conjunctive definition.

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18
Q

Formally, a rule is a logical implication A ^ B → C. How is it written in Prolog?

A

In Prolog, implication is written reversed using ‘:-’ instead of ‘←’, meaning C :- A, B.

C is the head of the rule (conclusion), while A, B is the body

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19
Q

What does father(X,Y) :- parent(X,Y), male(X) mean in Prolog?

A

X is the father of Y, if X is a parent of Y and X is male.

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20
Q

Is this valid syntax in Prolog?

greatgrandfather(X,Y) :- father(X,Z), grandparent(Z,Y)

A

Yes. It is the syntax for defining multiple relations in one statement.

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21
Q

It is not possible to assign constants to variables in Prolog.

A

False. The operation is called substitution and assigns a constant to a variable.

literal L = {parent(X,Y)}
substitution θ = {X/tom, Y/bob}

22
Q

What is Forward Chaining?

A

A logical reasoning method.

Process:

  • System examines which rules are applicable to the facts
  • when matching rule is found, new fact is generated & added to the fact collection

Process repeats until no new facts can be derived (“fix point”)

23
Q

What is the Elementary Production Principle?

A

A fundamental concept of Forward Chaining.

24
Q

What are the three main components of the Elementary Production Principle?

A
  1. Rule H :- B1, …, Bn (logical statement)
  2. Set of known facts F1, …, Fn (knowledge base)
  3. Substitution mapping θ the body literals to the known facts

Rule: parent(X, Y) :- father(X, Y).
Facts: father(john, mary)

25
Q

What is the Herbrand base?

A

A complete dictionary of all possible facts that can be stated in a given logical language.

It is built with predicates (like “parent_of”), constants (like specific names) and functions (create new terms by building all possible true/false statements e.g., parent(john, mary))

26
Q

What is backwards chaining?

A

Reasoning strategy that starts with desired conclusion and works backward to find supporting facts.

27
Q

What is the purpose of ontologies?

A

To encode the knowledge about a domain, form a common vocabulary and describe the semantics of its terms.

“An ontology is an explicit specification of a conceptualization”

28
Q

What are ontologies in CS?

A

A formalized description of a domain, a shared vocabulary or a logical theory

29
Q

What is a Semantic Network?

A

Multiple statements about the same entities.

30
Q

What does this RDF schema establish?

:Country a rdfs:Class .
:City a rdfs:Class .
:locatedIn a rdfs:Property .
:capitalOf rdfs:subPropertyOf :locatedIn .
:capitalOf rdfs:domain :City .
:capitalOf rdfs:range :Country .

:Madrid :capitalOf :Spain .

A

Definition of Terminology (T-Box)
* If x is the capital of y, then x must be a City and y must be a Country
* Being a capital of a country implies being located in that country (through the subproperty relationship)
* Only cities can be capitals (domain restriction)
* Cities can only be capitals of countries (range restriction)

Assertion (A-Box)
* Madrid is the capital of Spain.

31
Q

What are the elements of an RDF schema?

A
  • CLASS (e.g., :Country, :City)
  • PROPERTY (e.g., capitalOf)
  • DOMAIN (subject) and RANGE (object) constraints on property

  • Domain: :City (subject must be City)
  • Range: :Country (object must be Country)
32
Q

RDF Schemas allow for deductive reasoning.

A

True.

Given facts and rules, we can derive new facts. The corresponding tools are called reasoners.

33
Q

What is the opposite of deduction?

A

Induction, meaning deriving models from facts, e.g., data mining, machine learning

34
Q

What is OWL?

A

The Web Ontology Language, a syntactic extension of RDFS.

35
Q

How was OWL created and by whom?

A

The Web consortium W3C created OWL by fusing DAML (result of a European-wide project) and OIL (US-American development).

36
Q

What kinds of strategies for Knowledge Base Construction are there?

A
  • Domain-Specific (Experts)
  • Manual (Cyc)
  • Collaborative (Wikidata)
  • Automated (Watson)
37
Q

What was the first successful knowledge-intensive system?

A

DENDRAL project (Buchanan et al. 1969).

It was aiming to infer molecular structure from formula of the molecule and the mass spectrum.

37
Q

In which project did Feigenbaum discover the Knowledge Acquisition Bottleneck?

A

MYCIN for diagnosing blood infections and to antibiotics recommendations with adjusted dosage.

38
Q

What was R1/XCON?

A

An expert system for configuring computers at DEC, saved $40 Mio a year (McDermott, 1982)

39
Q

In 1984, the founder of Cyc (Douglas Lenat) estimated that 350 person years and 250,000 rules should do the job of collecting the essence of the world’s knowledge.

A

True.

40
Q

What is NELL?

A

NELL (Never-Ending Language Learning) is a computer system that continuously learns to read and understand web content.

41
Q

Which layers did Tim Berners-Lee’s vision include on top of the WWW (TCP-IP-DataLink)?

A
  1. XML
  2. RDF
  3. Ontology vocabulary
  4. Logic
  5. Proof
  6. Digital Signature
  7. Trust
42
Q
A
43
Q

Which technologies do the four major phases of Watson use?

A
  • NLP
  • Information Retrieval
  • Knowledge & Reasoning
  • ML
44
Q

What are the components of the Elementary Production Princinple (EPP)?

A
  1. Rule: A logical statement of the form H :- B1, …, Bn (Head:Body)
  2. Known facts: A set of facts F1, …, Fn that exist in the knowledge base
  3. Substitution: A mapping θ, unifies body literals with known facts

- Rule: parent(X, Y) :- father(X, Y).

- Facts: father(john, mary).

Applying EPP:
1. The substitution θ = {X/john, Y/mary} matches the body of the rule to the fact
2. Applying θ to the head of the rule: parent(X, Y) θ = parent(john, mary).
3. We derive the new fact: parent(john, mary)

45
Q

How does Backwards Chaining work?

A
  • starts with goal (or hypothesis)
  • works backward through rules to find facts that support goal (using DFS)
  • continue until all facts are proven true or the search fails
46
Q

What is the main difference in the automated construction of
knowledge bases in DBPedia and NELL?

A
  • DBpedia focuses on transforming semi-structured Wikipedia data into a structured knowledge base
  • NELL aims to learn how to read and extract knowledge from the broader web continuously
47
Q

Why is Manual KB Construction as in Cyc so difficult?

A
  • vast scale of knowledge
  • maintaining consistency
  • complexities of knowledge representation
  • need for continuous curation
48
Q

Why is logic not enough for knowledge representation?

A

It lacks expressiveness for uncertainty, context and relationships.

49
Q

What is the vision behind the Semantic Web as opposed to the WWW?

A
  • traditional web is primarily designed for human consumption and relies on keyword matching and hyperlinks for navigation
  • Semantic Web aims to create a web experience where machines can process information in ways that more closely mimic human comprehension

Introduction to AI (3/3) (4 decks)

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