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Summer 2019

Web Science & Social networks Signed Networks in Social Media

Professor: Prof. Dr. Wolfgang Nejdl Mentor: Philipp Kemkes Student: Masih Ghaderi

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Signed graph

A signed graph is a graph in which each edge has a positive or negative sign

In social psychology, signed graphs have been used to model social situations,

with positive edges representing friendships and negative edges enmities

between nodes, which represent people

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Introduction to signed networks

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Positive and negative links in online data

Discussion lists are filled with controversy and disagreement

A social network consists of a mixture of both positive and negative

interactions, co-existing in a single structure

Fundamental ingredients

1. Large-scale datasets from social applications

2. Theories of signed networks

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Introduction to signed networks

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Structural balance theory

Balance theory can be viewed as a model of likes and dislikes

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Introduction to signed networks

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Theories of signed networks: Balance

Balanced triangles with:

• three positive edges : “the friend of my friend is my friend”

• one positive and two negative edges : “the friend of my enemy is my enemy”

• “the enemy of my friend is my enemy”

• “the enemy of my enemy is my friend”

Extension (Weak structural balance)

• Eliminating the assumption that “the enemy of my enemy is my friend”

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Balanced Unbalanced

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Theories of signed networks: Status

A positive directed link indicates that the creator of the link views the recipient as

having higher status

A negative directed link indicates that the recipient is viewed as having lower

status.

Comparing the two theories

A links positively to a user B

B in turn links positively to a user C

If C then forms a link to A, what sign should we

expect this link to have?

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social network structures

Three widely-used Web sites:

1. The trust network of Epinions: users create signed directed relations to each

other indicating trust or distrust.

2. The social network of the technology blog Slashdot: users designate others as

“friends” or “foes”

3. The network defined by votes for Wikipedia admin candidates

A positive vote as corresponding to a positive link from the

voter to the candidate

A negative vote as a negative link.

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Datasets

In all networks the background proportion of positive edges is about the same,

with roughly 80% of the edges having a positive sign.

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Datasets

the counts of the four possible signed

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Analyzing positive and negative ties

Characterize the parts of the network in which positive ties are more likely to

occur

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Conclusion

One of the best scientific research in two theories of signed social networks

(balance and status)

Social networks often reflect a mixture of positive and negative inks

These two theories make different predictions for the frequency of different

patterns of signed links

Differences in results between the datasets highlight some interesting aspects

of how the sites present information

Strong evidence for a weak form of structural balance when the networks

are viewed as undirected graphs

Balance theory no longer apply when the networks are viewed as directed

graphs

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Thank you