Jeremy Rubin <jeremy.l.ru...@gmail.com> writes: > Hi Rusty, > > Please see my post in the other email thread > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-February/019886.html > > The differences in this regard are several, and worth understanding beyond > "you can iterate CTV". I'd note a few clear examples for showing that "CTV > is just as powerful" is not a valid claim: > > 1) CTV requires the contract to be fully enumerated and is non-recursive. > For example, a simple contract that allows n participants to take an action > in any order requires factorially many pre-computations, not just linear or > constant. For reference, 24! is about 2**80. Whereas for a more > interpretive covenant -- which is often introduced with the features for > recursion -- you can compute the programs for these addresses in constant > time. > 2) CTV requires the contract to be fully enumerated: For example, a simple > contract one could write is "Output 0 script matches Output 1", and the set > of outcomes is again unbounded a-priori. With CTV you need to know the set > of pairs you'd like to be able to expand to a-priori > 3) Combining 1 and 2, you could imagine recursing on an open-ended thing > like creating many identical outputs over time but not constraining what > those outputs are. E.g., Output 0 matches Input 0, Output 1 matches Output > 2.
Oh agreed. It was distinction of "recursive" vs "not recursive" which was less useful in this context. "limited to complete enumeration" is the more useful distinction: it's a bright line between CTV and TXHASH IMHO. > I'll close by repeating : Whether that [the recursive/open ended > properties] is an issue or not precluding this sort of design or not, I > defer to others. Yeah. There's been some feeling that complex scripting is bad, because people can lose money (see the various attempts to defang SIGHASH_NOINPUT). I reject that; since script exists, we've crossed the Rubicon, so let's make the tools as clean and clear as we can. Cheers! Rusty. _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
