Quote from: Rannasha on February 20, 2014, 11:29:06 PM

That seems like a decent condition as a prerequisite, but it hardly describes what is actually going on. That set of expressions simply states that the chance of loss of value should be zero while there is a strictly positive chance of profit. In other words: There has to be the chance for risk-free profit.

I felt that it would be redundant to rewrite a descriptive text for an arbitrage opportunity, as one is given at the start of this thread. However the conditions given by Björk defines arbitrage which is true in any situation, not only trading assets on a market.
Further I'm fully aware that there exist different formal definitions of arbitrage, I prefer the one given by Björk since I don't like to lose money when hustling.