cpts121-1-1 - CptS 121 Fall 09 Lecture 1-1 Welcome to CptS...

1
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
CptS 121 Fall ‘09 Lecture 1-1
Welcome to CptS 121 and WSU!
Lecture Outline
I. Introduction to computer science
II. Introduction to this course

2
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
What is Computer Science?

Computer science is
a)
the study of computers.
b)
the study of computer programming.
c)
the study of the uses and applications of
computers and software.
d)
None of the above.

The correct answer is...

d) None of the above!

Then what is it?

3
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
What is Computer Science (cont.)

Computer science is the study of
algorithms

What is an algorithm?

Can anyone give me an example of an
algorithm?

4
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
What is Computer Science (cont.)

What is an algorithm?

A sequence of instructions that solve a
problem

Why are algorithms so important to
computer science?

If we can specify an algorithm, we can
automate the solution

A computing agent (human, robot, computer)
can interpret and carry out the instructions
to solve the problem

5
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
Can Algorithms Solve All Problems?

Some problems are unsolvable

No algorithmic solution exists

Some problems have no tractable
solution, meaning no solution can be
found in a reasonable amount of time

“Brute-force” algorithms

We simply don’t know an algorithm that
will solve some problems

Many “artificial intelligence” problems rely
on heuristic search

6
C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
Formal Definition of Algorithm

A well ordered collection. . .

Of unambiguous and effectively
computable operations. . .

That produces a result. . .

And halts in a finite amount of time.

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C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
Is this an Algorithm?

Add flour until paste is sticky

Knead until firm

Roll thin and cut

Bake in a medium oven until light brown

Place on rack until cool
No! Why not?
Hint: Are all operations unambiguous?

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C ptS  121 L1-1 – 8/24/09
Pro f. C hris  Hundhaus e n
Is this an Algorithm?