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1. Explaining and understanding a physical phenomena usually leads to predictions: Examples: the Higgs Boson, photo electric ….
2. Theory without predictions of new phenomena andthe possibility of testing the predictions is usually not regarded as a valid theory!
3. I will present three examples from my current field: (i) Early predicting of epidemic spreading (ii) Abrupt breakdown of a system of systems represented as “network of networks”
(iii) Early prediction of El-Nino events (Unpublished)
Explain or Predict
Explain AND Predict
SHLOMO HAVLIN Bar-Ilan University
Based on theoretical paper of Cohen, Havlin and ben-Avraham, PRL 91, 247901 (2003)
Single and coupled networks: Robustness
P∞
1
0 1
Continuous abrupt
cp
Remove randomly (or targeted) afraction nodes1 p−
P∞ Size of the largest connected component (cluster)
p
Giant component and breakdownthresholds are predicted for these models
Single networks:Continuous transition
0 cp
ER
Coupled networks:New paradigm-Abrupt transitionCascading Failures
Single ERCoupled
Cascades,Suddenbreakdown
Breakdown threshold cp
[1 exp( )]P p k P∞ ∞= − −
Network of Networks (tree)
Buldyrev et al Nature (2010)Gao et al PRL (2011)
n=5
For ER, full coupling ,ALL loopless topologies (chain, star, tree):
Vulnerability increases significantly with n
n=1 known ER- 2nd order
1/cp k=
[1 exp( )]nP p k P∞ ∞= − − P∞
ik k=
n=1
n=2
n=5