KBAI 笔记 03 Semantic Networks

Preview Knowledge representation

Representation has two things

• The Knowledge
  • vocabulary
• The Content that goes into the presentation
  AI Has many representations and each has its own affordance and constraint.

Introduction to Semantic Networks

Example: Find Knowledge representations for each figure Semantic Network of A and B

• A: label objects in A as nodes x, y and z and describe the relationship between these objects with links.
• B: Do the same to B, label objects and the relationship
• between A and B: actions taken were described with the dash line.

Another example Excersice

• Key: use only the existing vocabulary

Excersie

• the relationship of objects between C and 5 is not the same

Structure of Semantic Networks

Characteristics of Good Representations

goo representations is food label a good representation?

Guards and Prisoners problem

Guards and Prisoners problem Solving the Guards and Prisoners problem

• need to find out the legal and productive way of moving prisoners and guards from the left to the right side.

Solving the Guards and Prisoners Problem

• the above moves were all legal, but two of them were not productive because they appeared in the previous steps.
• the power of semantic network representation is that it makes all the constraints of the states explicit and allows the problem be solved in a systematical way

Solution of the Guard and Prisoner Problem

• Please note that the state of the boat is also part of the system so that step 2 and 5 are not the same.

Represent & Reason for Analogy Problems

Back to the original question,

Example: Find Knowledge representations for each figure 5 is not the correct answer

we know that 5 is not the correct answer because the semantic representation of A->B does not match C->5.

Now let's try C -> 2.

Is 5 the correct answer?

• we choose 5 as the best answer because the semantic network representation of C -> 5 matches the exactly that of A -> B. What if we don't find a 100% match?

Exercise: How do we choose a match?

exercise

• 5 is the answer: inner object disappear
• 3 can also be an answer: outer object disappear and inner object expand.
• Why most of the people will choose 5 instead of 3?

Choosing Matches by Weights

apply weights on exercise of weights: which on is the answer?

• 2 and 4 can both be an answer. However, C -> 2 is reflection which weights 4 points and C -> 4 is rotations which worth 3 points. In this case, 2 is the best answer because it has better weight

Connection

• To solve the problem, we need to save the representation of A -> B into the memory, also calculate the representation of C to all the options.
• The correspondent problem: one object in A corresponds to which object in B?
• In KBAI, the emphasis is on the relationships between object, not the features of an object (another weighting problem.

Assignment 1

The Cognitive Connection

How semantic networks connected to human cognition?

1. Semantic networks are kind of knowledge representation which can be used to represent knowledge and problems, thus can be used to solve the problem. The human mind can also represent knowledge and problem, and solve problems.
2. Semantic networks can expand, like human memory. initial input could activate certain nodes, expand to related nodes on the semantic networks, and form a pathway. [John wants to become rich. He got a gun]

20170121 first draft
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