1. Lorem Ipsum Dolor Structure and tie strengths in mobile communication network

2. Introduction ❖ Backgrounds: ❖ Past research: questionnaire data ❖ This research: mobile phones record ❖ Communicating network: strength and topology ❖ Three main research ❖ Relationship between tie strength and topology ❖ Network’s stability if ties are removed ❖ Spread of information within the network

3. Basic Knowledge ❖ Elements: ❖ Undirected, reciprocal link ❖ Strength: aggregate duration of calls(w)

4. 1.Relationship between strength and topology Tie Strength DistributionMCG Distribution

5. 1.Relationship between strength and topology Global efficiency HypothesisWeak ties Hypothesis Dyadic Hypothesis Tie strength is driven by the local network structure Tie strength is independent with network structure Tie strength is driven by the whole network topology

6. 1.Relationship between strength and topology Relation between overlap and cumulative strength Topological overlap

7. 2.Network’s stability if ties are removed Remove links with overlapRemove links with strength The removal of weak ties lead to a sudden, phase transition-driven collapse The removal of the strong ties results only in the network’s gradual shrinking

8. 3.Spread of information within network A: Information transfer is faster on the equal network B: Rapid diffusion within a single community C: information transfer is through ties of intermediate strength D: In the control group, infections are among weak ties E: Communities connected by weak ties are only rarely infected F: Information mainly follows the sh ortest paths

9. Conclusion ❖ 1. Tie strengths correlate with the local network structure around the tie, both the dyadic hypothesis and the global efficiency principle are unable to account for the empirical observations ❖ 2. The removal of the weak ties results in a phase transition-like network collapse ❖ 3. Information are transferred mainly by intermediate ties ❖ 4. weak ties appear to be crucial for maintaining the network’s structural integrity, but strong ties plays an important role in maintaining local communities ❖ Recommend Paper: ❖ Jacob, Barak, Eitan: Talk of the Network: A Complex Systems Look at the Underlying Process of Word-of-Mouth. Marketing Letters 12.3(Aug,2001) 211 ❖ Zhang, Wu, Feng, Xiong: Information propagation in online social networks: a tie-strength perspective, knowledge and information system,32.3(sep,2012)589-608