This document provides an introduction to network theory and its major concepts and research areas. It discusses what networks are, common network models, and seminal works that helped establish the field, including sociograms, the small world phenomenon, and theories of strong and weak social ties. Major areas of research covered include distance and effective distance between nodes, the size of interpersonal environments, degrees of separation, and how weak ties help integrate social systems. The document concludes with brief sections on network optimization and analysis.

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Network Theory
LEARNING OBJECTIVES
1
An Introduction
2
What is a Network?
3
Network Models
4
Network Theory
5
Social Networks
6
Major Research in Network Theory
7
Moreno’s Sociograms
8
The Small World

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Cartwright and Harary
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Distance between any Two Nodes
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The Effective Distance between Nodes
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The Size of the Interpersonal Environment
13
Six Degrees of Separation
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Strength of Weak Ties
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Weak Ties Help to Integrate Social Systems
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Network Optimization
17
Network Analysis
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References