Quote from: jgarzik on May 09, 2013, 04:44:28 PM

Quote from: jonytk on May 09, 2013, 04:21:58 PM

It should never allow you to reemplace a transaction, or to change outputs,
it should allow you to give more priority to a transaction that it's stuck on the limbo of 0 fee/smaller fee transactions.

Only replace the transaction if it's the same transaction with bigger fee. to the same outputs.

Any other thing is not bitcoin, btc is not reversible.
or you just killed satoshi dice.

Zero-confirmation transactions were never safe. Note that Satoshi DICE apparently waits for confirmations, on higher value bets -- an admission that SD themselves know zero-conf are not safe.

Yup. I've spoken with evoorhees about this issue and while I don't know what their plans are exactly they had no objections. In fact, out of the roughly half dozen people running services I have either contacted, or who have contacted myself or John Dillon, nobody has actually asked us not to implement replace-by-fee. I don't want to pretend I'm speaking for them, but I suspect the few merchants that actually need zero-conf security would like to see a genuinely secure solutions be implemented like trusted computing, fidelity bonds w/ double-spend fraud proofs and off-chain mechanisms rather than the current half-measure of hoping everyone follows a de-facto standard.

Quote from: jgarzik on May 09, 2013, 04:44:28 PM

However, with regards to transaction replacement, it should be noted that it introduces race conditions that increase non-determinism.

The first step towards improved determinism is, instead, making transactions expire after a certain amount of time in memory pools, without being mined.

Mind expanding a bit on what you mean by non-determinism?