## The martingale approach to disorder irrelevance for pinning models.(English)Zbl 1221.82058

Summary: We present a very simple and self-contained proof of disorder irrelevance for inhomogeneous pinning models with return exponent alpha in $$(0,1/2)$$. We also give a new upper bound for the contact fraction of the disordered model at criticality.

### MSC:

 82B44 Disordered systems (random Ising models, random Schrödinger operators, etc.) in equilibrium statistical mechanics 60K37 Processes in random environments 60K05 Renewal theory
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