A buyer b will start by requesting bids for a good g. She will then accept all bids for good g and will pick the seller:
The function 
returns the value the buyer expects to get if
she buys good g at a price of p. It is learned using a simple form
of reinforcement learning, namely:
where 
is the learning rate, p is the price b paid for the
good, and q is the quality she ascribed to it. The learning rate is
initially set to 1 and, like 
, is decreased until it
reaches some fixed minimum value 
.