Intro to computer science module 1

Foundations of Computer Science and Software Engineering

module 1/30

WALID S. SABA


ALBERT EINSTIEN

TO THE TEACHER


TO THE STUDENT

SOCRATES


About this CourseThis is an introductory course that will introduce computer science and software engineering to the novice, and it is also a course that will teach even veteran computer scientists some new concepts, or explain concepts they thought they understood well. Concepts are introduced with hands on experience using object-oriented pseudo code (which can very easily be translated to C#, Java, C++, etc.) and functional programming pseudo code (which can easily be translated into F#, Erlang, Python, Haskell, etc.)

About the AuthorWalid Saba has 20 years of experience in information technology, where he worked at such places as the American Institutes for Research, AT&T Bell Labs, Metlife, Nortel Networks, IBM and Cognos. He has also spent 7 years in academia where he has taught computer science at Carelton University, the New Jersey Institute of Technology, the University of Windsor, and the American University of Beirut. He has published over 30 technical articles, including an award wining paper that he recieved at KI-2008 in Germany. Walid holds a PhD in Computer Science which he obtained from Carleton University in1999


Other Courses by the Authoro Logic, Semantics and Natural Language Processingo Ontology, Data Modeling and Knowledge Representationo Object-Oriented Software Engineeringo Advanced Data Structures and Algorithm Design


Legends

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Computer Science is ultimately the science of representing and reasoning with data, information, and knowledge

MODULE 1 (20 minutes)

WHAT IS THE SCIENCE OF COMPUTING CONCERNED WITH?


A LITTLE STORY

An ancient tribe once sent a wise old man up the mountain to seek God’s wisdom. After some time the wise old man came back claiming that God had supplied him with all the knowledge in the world, which he carved on his cane as a strange symbol that looked like this:

Can this be true?

Can this strange symbol really represent all the knowledge in the world?


A LITTLE STORY


Can this be true?


What do you think?

Can this strange symbol represent all the knowledge in the world (Yes, or No)? What is your reasoning in either case?


One can argue that, yes, this can be true ...How?

Well, all of our knowledge (all of our mental creations),



Well, all of our knowledge (all of our mental creations), are scripts, symbols, and text



Well, all of our knowledge (all of our mental creations), are scripts, symbols, and text, paintings



Well, all of our knowledge (all of our mental creations), are scripts, symbols, and text, paintings, sounds and melodies



Well, all of our knowledge (all of our mental creations), are scripts, symbols, and text, paintings, sounds and melodies, movies and animations, etc...


But you have all seen these objects on your digital devices (TVs, computers, phones, tablets, etc.)

The reason you are able to do so is that these objects can all be digitized


We mean they can all be represented as a sequences of 1’s and 0’s

But what do we mean by “all of these objects can be digitized”?


We mean they can all be represented as a sequences of 1’s and 0’s

But what do we mean by “all of these objects can be digitized”?

Two words in the heading of this slide make up a phrase that this slide is specifically talking about. What are they?

Can you guess how 1 and 0 are manifested inside a digital device?


In the end, a binary sequence is nothing but a number.

The decimal value of any binary sequence such as is computed as follows:


But, in the end, a binary sequence is nothing but a number.


Note that in the case of a binary sequence, the decimal value is obtained by computing some values and either adding them to the total (multiply them by 1), or ignoring them from the total (multiplying them by 0). In other words, either we are ignoring that position, or we are giving it some value!




According to the above definition, what is the decimal value of the binary sequence “101101”?




How would you modify the above definition to compute the decimal value of a sequence of octal digits (that is, a sequence of digits in base 8), where 0, 1, 2, 3, 4, 5, 6 and 7 are the only digits?




You will soon see learn how to write a very simple, though not too efficient function (or program) that implements the above definition, and later how to write the more efficient one.


Let’s summarize what we have so far



All of our mental creations can be



1100010101001110001111100100000111010110101 ...


digitized into a binary sequence

of 1’s and 0’s



1100010101001110001111100100000111010110101 ...



of 1’s and 0’s

A binary sequence, not matter how

large, is in the end some number

72619283749824723947...



72619283749824723947...

A binary sequence, not matter how

large, is in the end some number

This number is so large that we want

to represent it using this symbol

1100010101001110001111100100000111010110101 ...



of 1’s and 0’s


NOW LET’S REPEAT THE STORY AND ASK THE SAME QUESTION AGAIN


What is your answer now? Can this be true?



NOW LET’S REPEAT THE STORY AND ASK THE SAME QUESTION AGAIN


What is your answer now? Can this be true?


Admittedly, the question is a bit tricky. Some of you might have answered yes, given that we showed that all mental creations can be digitized and stored as a binary sequence, which in the end a single value (or that symbol). Others might have said no, this cannot be done, but they do not have a formal proof.

Actually, the answer, which will be discussed next, is that at this point in the state-of-the-art, is partially YES and partially NO. Let’s see why ...


Here’s the answer ...Yes, the symbol below can represent all the DATA in the world, and some INFORMATION, but not all the KNOWLEDGE in the world

o Yes, we can digitize, store (given enough memory), and manipulate all the DATA in the world

o With creative data modeling, we can represent and manipulate INFORMATION about this data

o But computers, at this point, do not KNOW what they know! So, what is stored is data and information, but not knowledge, and this is the quest of computing science!


DATA, INFORMATION, and KNOWLEDGE

So what is the difference between DATA, INFORMATION, and KNOWLEDGE?




Data is just a set of values (of some variables). That’s it!





Some examples of data: raw figures, numbers, or symbols that represent the value of something





Some examples of data: raw figures, numbers, or symbols that represent the value of something

In programming, as we will later see, these variables, that have some data objects as their values, also have types. For example, the type of a data value could be a number, a character, a string, a set, etc.


DATAA datum such as ‘45’ can represent the value of many variables:



Age



Age Number of branches in California



Number of UN resolutions vetoed by the US between 1966 & 1985

Age Number of branches in California


DATAA sequence of characters (also called a string) such as “ABBA” can stands for:


Name of a Swedish pop rock band



God, or “the Father” in Aramaic (Jesus called his Father Abba ...)




God, or “the Father” in Aramaic (Jesus called his Father Abba ...)


DATA

One of the 4-letter palindromes that

can be made out of the letters ‘A’ and ‘B’

A sequence of characters (also called a string) such as “ABBA” can stands for:


Put simply, INFORMATION is organized DATA. Modeling data in a certain structure that is meaningful to us makes information out of data.

INFORMATION

hmmm


Too much data


INFORMATION


What to do?


INFORMATION


Higher a data

modeller!


INFORMATION



INFORMATION



INFORMATION



INFORMATION


Some examples of organizing data into information ...INFORMATION

The datum 2 and the datum 3 can be organized in a pair (2,3) to represent a point in a 2-dimensional space (2,3)

(5,1)

The datum 1 and the datum 5 can also be grouped in a pair to represent another point

The straight line connecting (5,1) and (2,3) can be represented by a list of points {(5,1), (2,3), … }


As another example, consider the following structure (or record, as these structures are typically referred to)

INFORMATION

This structure, made-up of five data items, might represent a record of information for a certain person:



INFORMATION


o who is 45 years old,



INFORMATION


o who is 45 years old, o who is a female,



INFORMATION


o who is 45 years old, o who is a female, o whose name is Mary,



INFORMATION


o who is 45 years old, o who is a female, o whose name is Mary, o whose is an Engineer, and



INFORMATION


o who is 45 years old, o who is a female, o whose name is Mary, o whose is an Engineer, and o who has a salary of 45,000


We can organize such data further. For example, the following set of records might represent (part of the) information about employees in a certain company

INFORMATION


The question now is this: if data is raw figures, numbers or symbols about some facts, and information is a meaningful organization of data, then what is knowledge?

DATA, INFORMATION and KNOWLEDGE




Information is data organized into facts.




Knowledge

Knowledge is information about information, or conditional facts





Knowledge

Knowledge is information about information, or conditional facts



IN SUMMARY …


IN SUMMARY …


IN SUMMARY …


It is a bit early to discuss the real difference between data, information and knowledge. After all, this course is an introduction to Computer Science and Software Engineering, not an advanced course in Artificial Intelligence.


And, we did not even start the course yet!But now we know a little bit about data, information, and knowledge

COMPUTER SCIENCE AS A DESCIPLINE

Introduction to Computer Science

COMPUTER SCIENCEAs a formal subject of study, Computer Science started in 1950’s, but the roots of Computer Science can perhaps be traced back to years of work in philosophy, mathematical logic, linguistics, psychology, biology and physics

Pioneers that have defined the field were either mathematicians, such as Godel and Turing; physicists, such as Von Neumann; philosophers, such Gottlob Frege; logicians, such as David Boole; or Biologists, such as McCulloch and Pitts


COMPUTER SCIENCEAlthough it is one of the newest and fastest developing areas of human knowledge, Computer Science deals with many of the scientific issues that have occupied the most brilliant minds for thousands of years, such as



- the relationship between data, information and knowledge,



- the relationship between data, information and knowledge,- issues related to learning, memory, and cognition,



- the relationship between data, information and knowledge,- issues related to learning, memory, and cognition,- issues of representation, language, meaning, complexity,


COMPUTER SCIENCEIn dealing with such issues that have occupied the minds of the most brilliant philosophers and scientists for thousands of years, computer scientists develop new technologies and applications that are immediately applicable to almost every aspect of our daily lives.




allow us to perform remote and real-time banking

Computer scientists have analyzed, designed, and implemented systems that




buy and sell products across the world while sitting home





buy and sell products across the world while sitting home

help doctors perform diagnosis as well as perform surgery


COMPUTER SCIENCEAdvanced computer algorithms are also behind the systems that




control space shuttles



control space shuttles control and maneuver robotic devices roaming planets that are thousands of miles away



control space shuttles perform wireless communication

control and maneuver robotic devices roaming planets that are thousands of miles away

COMPUTER SCIENCE vs. COMPUTER PROGRAMMING

Computer programming is thus one of the things computer scientists do – it is only the ‘tool’ by which computer scientists ‘implement’ their ideas, their models, and their designs


Computer scientists make machines (computers) do things, and they only way these machines will do anything (since they do not yet understand everyday spoken languages) is by instructing them in formal languages they understand – these languages are called ‘programming languages’.

http://en.wikipedia.org/wiki/Computer_programming

Introduction to Computer ScienceSPECIALTIES IN COMPUTER SCIENCE

Computer science is a rich discipline of study and there are many subfields in computer science that one can spend a lifetime mastering. Some of the main areas of computer science are:

o SOFTWARE ENGINEERINGo ARTIFICIAL INTELLIGENCEo DATA MINING AND MACHINE LEARNINGo COMPUTER GRAPHICS AND VISUALIZATIONo VIRTUAL REALITYo TELECOM AND COMPUTER NETWORKSo COMPUTER VISIONo COMPUTER SECURITY AND CYRPTOGRAPHYo DATA COMPRESSIONo PARALLEL AND DISTRIBUTED SYSTEMSo COMPUTER ARCHITECTURE AND ENGINEERINGo IMAGE PROCESSING AND PATTERN RECOGNITION

Introduction to Computer ScienceSPECIALTIES IN COMPUTER SCIENCE

Computer science is a rich discipline of study and there are many subfields in computer science that one can spend a lifetime mastering. Some of the main areas of computer science are:

o SOFTWARE ENGINEERINGo ARTIFICIAL INTELLIGENCEo DATA MINING AND MACHINE LEARNINGo COMPUTER GRAPHICS AND VISUALIZATIONo VIRTUAL REALITYo TELECOM AND COMPUTER NETWORKSo COMPUTER VISIONo COMPUTER SECURITY AND CYRPTOGRAPHYo DATA COMPRESSIONo PARALLEL AND DISTRIBUTED SYSTEMSo COMPUTER ARCHITECTURE AND ENGINEERINGo IMAGE PROCESSING AND PATTERN RECOGNITION

In what subfield of Computer Science would you like to become an expert?

You are right if you are thinking that it is a bit too early to decide!


COMPUTER SCIENCE

Before becoming a specialist in any subfield of computer science, let us start learning the basics

By the time you finish all the modules in this course you will be in a position to start learning any subfield of computer science in more details

Our main hope is that the key concepts that are covered this course, and which form the foundations of many advanced topics in computer science, are well understood. We further hope that the material presented in this course inspires you to truly become a computer scientist who might one day solve one or more open problems in this exciting field of study


o Basic Introduction to Logico Sets, Relations and Functionso Inductive (Recursive) Data Structureso Recursion, Induction, and Recursive Programso Relations, Functions and Relational Algebrao Complexity Analysiso Data Types, Types of Programs and Type Inferenceso Higher-Order (Generic) Programming and Programming Patternso Languages, Grammars and Semantic Analysiso Introduction to Automata: Machines and Computation

CONTENT OF THIS COURSE

PART 1 – FOUNDATIONS


o Basic Data Structures (lists, trees, stacks, queues, graphs)o Basic Algorithms (searching and sorting algorithms)o Hashing techniqueso Applications of algorithms and data structures

CONTENT OF THIS COURSE

PART 2 – BASIC ALGORITHMS AND DATA STURCTURES

o Abstract Data Types (ADTs)o From ADTs to Classes: The Notion and Use of Polymorphismo Object Modeling: Inheritance, Containment and Delegationo Object-Oriented Analysis and Designo Design Heuristics and Design Patterns

PART 3 – OBJECT-ORIENTED SOFTWARE ENGINEERING


END OF MODULE 1

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Education

Intro to computer science module 1