Optimistic replication algorithms allow data presented to users to be stale (non-up-to-date) but in a controlled way: they propagate updates in background and allow any replica to be accessed directly most of the time. When the timely propagation of updates to remote distributed replicas is an important issue, it is preferable that a replica gets the same update twice than it does not receive i...

There is an abundant literature in finance on overconfidence, however there exists a different psychological trait well known to financial practitioners and psychologists [see Hilton at al. (2004)] which is optimism. This trait has received little attention. Our paper analyses the consequences of optimism and pessimism on financial markets. We develop a general model of optimism/pessimism where...