Arbitrage and Hedging in Model-Independent Markets with Frictions

We provide a Fundamental Theorem of Asset Pricing and a Superhedging Theorem
for a model independent discrete time financial market with proportional
transaction costs. We consider a probability-free version of the Robust No
Arbitrage condition introduced in Schachermayer ['04] and show that this is
equivalent to the existence of Consistent Price Systems. Moreover, we prove
that the superhedging price for a claim g coincides with the frictionless
superhedging price of g for a suitable process in the bid-ask spread.