Abstract
We provide the first mathematical proof that the connective constant of the hexagonal lattice is equal to $\sqrt{2+\sqrt{2}}$. This value has been derived nonrigorously by B. Nienhuis in 1982, using Coulomb gas approach from theoretical physics. Our proof uses a parafermionic observable for the selfavoiding walk, which satisfies a half of the discrete CauchyRiemann relations. Establishing the other half of the relations (which conjecturally holds in the scaling limit) would also imply convergence of the selfavoiding walk to SLE($8/3$).

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@misc{BGG,
author={Beaton, N. and de Gier, J. and Guttmann, A.},
TITLE={The critical fugacity for surface adsorption of {SAW} on the honeycomb lattice is $1+\sqrt{2}$},
YEAR={2011},
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} 
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ZBLCOMMENT = {BIBPROC: YEAR doesn't match found ZBLNUMBER},
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