Chapter 11Artificial Intelligence

Introduction to CS

1st Semester, 2015 Sanghyun Park

Outline Introduction Understanding Images Reasoning Artificial Neural Networks Genetic Algorithms Other Areas of Research

Definition ________________ (AI) is a branch of science which

deals with helping machines find solutions to complex problems in a more _________ fashion

This generally involves borrowing characteristics from human _________, and applying them as _________ in a computer friendly way

AI is generally associated with ________ science, but it has many important links with other fields such as math, psychology, cognition, and biology

Motivation Computers are fundamentally well suited to perform

__________ tasks efficiently and reliably

Unlike humans, computers have trouble understanding ______ situations, and _______ to new situations

AI aims to improve machine behavior in tackling such complex tasks

Much of AI research aims to understand our intelligent behavior. Humans have an interesting approach to problem-solving, based on _______ thought, high-level deliberative _________ and pattern recognition

Eight-Puzzle Machine

The design of eight-puzzle machine provides a basisfor presenting the topics of the following two sections

Understanding Images (1/2) The first intelligent behavior is to understand the _____ in

order to extract the status of the puzzle

Our machine can detect which tile is in which positionby ____-by-____ comparisons

But it requires a certain degree of ________ among the style, size and orientation of the symbols being read

Another approach is based on the matching of the ________ characteristics

This method involves two steps Extract the features from the image being processed Compare the features to those of known symbols

Understanding Images (2/2) The task of understanding general images is usually

approached as a two-step process: image processing and image analysis

Image processing refers to ________ characteristics of the image Edge enhancement Region finding Smoothing

Image analysis refers to the process of ____________ what these characteristics mean

Reasoning Once our puzzle-solving machine has deciphered the

_______ of the tiles, its task becomes that of figuring out what ______ are required to solve the puzzle

An approach to this problem is to __________ the machine with solutions to all possible arrangements of the tiles

However this approach is not possible when time and storage _________ are considered

Therefore the machine must be programmed to perform elementary _________ activities

Production Systems A large class of reasoning problems have common

characteristics; these common characteristics are isolated in a system known as a _________ system

A production system consists of three main components A collection of _____: each state is a situation that might occur

in the application environment A collection of _________: a production is an operation to shift

the system from one state to another A _____ system: it consists of the logic that solves the problem

of moving the system from the _____ state to the goal state

State Graph An important concept in the development of a control

system is that of a _____ graph

A state graph consists of a collection of nodes representing the _____ in the system connected by arrows representing the __________ that shift the system from one state to another

When viewed in terms of the state graph, the problem faced by the control system becomes that of finding a sequence of _____ that leads from the start state to the ____ state

State Graph: Example

Search Trees We have seen that the control system’s job involves

searching the state graph to find a ____ from the start node to the goal

One strategy is to construct a ______ tree that consists of the part of the state graph that has been __________ by the control system

Let us consider the following start state;

Sample Search Tree (1/2)

Sample Search Tree (2/2)

Heuristics (1/2) The search tree can become quite _____ if the goal is

not quickly reached

One strategy is to change the order in which the search tree is constructed; rather than building it as a _______-first manner, we can pursue the more promising paths to greater depths --- _____-first construction

We need a way of identifying which of several states appears to be the most ________

Our approach is to use a _______, which is a quantitative value associated with each state that estimates the _______ from that state to the goal

Heuristics (2/2) A simple heuristic in the case of the eight-puzzle would

be to estimate the distance to the goal by _______ the number of tiles that are out of place

However this heuristic does not take into account how ___ out of position the tiles are

A better heuristic is to measure the distance each tile is from its destination and add these values to obtain a single quantity

Heuristic value is __

Algorithm for Control SystemUsing Heuristics

Example:Beginning of Heuristic Search

Example:Search Tree After Two Passes

Example:Search Tree After Three Passes

Example:Complete Search Tree

Artificial Neural Networks CPUs that execute sequences of instructions do not

seem capable of perceiving and reasoning like _______

Many researchers are turning to machines with other architectures; one of these is the artificial neural network

Artificial neural networks are constructed from many processing units, in a manner that models networks of _______ in living biological systems

A Neuron in a Living Biological System

The signals transmitted via a cell’s ____ reflect whether the cell is in an ________ or excited state

This state is determined by the combination of signals received by the cell’s _________

Activities Within a Processing Unit A processing unit is a simple device that mimics this basic

understanding of the biological _______ It produces an output of 1 or 0, depending on whether its

________ input exceeds a given ________ value This effective input is a weighted sum of the actual inputs

Weights Within a Processing Unit Representation of a processing unit

The fact that a weight can be positive or negative means that the corresponding input can have either an inhibiting or _______ effect on the receiving unit

Actual size of the weight controls the _______ of effect By _________ the values of the weights throughout an

artificial neural network, we can program the network to respond to different inputs in a predetermined manner

Example Networks

1 if two inputs differ,0 otherwise

1 if both inputs are 1,0 otherwise

Genetic Algorithms Genetic algorithm applies our understanding of natural

_______ to the problem-solving task

This approach is to intermix the ____ performers withina collection of proposed solutions to obtain another generation of better proposed solutions

By repeating this process, one hopes to simulate the __________ process and ultimately obtain solution

Process in Genetic Algorithms (1/2) One finds a way to represent potential solutions as

______ of symbols

A collection of potential solutions is generated and tested

The better solutions from this collection are then ______ to form a new generation of potential solutions

At times random __________ may be inserted during the crossing process

Process in Genetic Algorithms (2/2)

Evolutionary Programming The goal is to develop programs by allowing them to

_______ rather than by explicitly writing them

An important step in this setting is to find ways in which parts of programs can be ____________ to produce meaningful new programs

The ________ programming paradigm has proved useful in this context

A major problem is to identify the “best performers” out of a group of programs of which none seem to be anywhere close to the desired product

Natural Language Processing (NLP) A statement in a natural language can have ________

meanings depending on its context To unravel the meaning of a statement in a natural

language therefore requires several levels of analysis The first level is ________ analysis that performs parsing

to identify the grammatical role of each word The next level is _________ analysis that identifies the

semantic role of each word in the statement“Mary gave John a card” = “John got a card from Mary”

A third level is _________ analysis where the context of the sentence is brought into the understanding process“The bat flew from his hand”

Information Retrieval And Extraction Another area of research in NLP concerns an ______

document rather than individual sentences Information retrieval refers to the task of identifying

documents that ______ to the topic at hand Information extraction refers to the task of extracting

information from documents so that it takes a formthat is useful in other applications

One such form is known as a _______ that is essentially a questionnaire in which specifics are recorded

Another form in which information extractors record information is known as _________ net

A Semantic Net

Robotics The goal of the early research in robotics was to develop

economically viable ________ line robots that could increase both productivity and consistency

Today, a major goal of research in robotics is to build __________ robots that can maintain their balance, walk up stairs, and navigate through rough terrain

Many creative techniques are being applied.One is the application of ___________ theories to robot development, which generated the field of evolutionary robotics

Database Systems AI techniques are applied to traditional DB systems to

provide better services. DB techniques are applied in AI projects to handle ________ amounts of knowledge

One topic is to identify and retrieve information that is ______ to a topic rather than merely the information that is explicitly requested

Another topic is the development of data storage and retrieval system that can provide information that is _______ by the stored data rather than merely respond with information that is explicitly stored

Expert Systems Expert systems are software packages designed to assist

humans in situations where an expert in a specific area is required

These systems simulate the cause-and-effect reasoning that experts would accomplish if confronted with the same situations

A major task in constructing an expert system is to obtain the required __________ from an expert

A next task is to _______ the knowledge into a format compatible with a software system

Knowledge base vs. inference engine