Ah, interesting. reorgs have the potential to be quite catastrophic! In this hypothetical, I think it would be even worse for grin with this approach because inputs are only merged with other very recent transactions. Monero has the entire history to draw from for its ring signatures and would be less likely to be affected by a chain split/reorg. Still though, I think they bias toward selecting recent transactions… it’s unclear to me.
What if grin adopted a kind of ring signature scheme? would cut through still be possible? imagine an output is spent and creates a ring signature with n possible inputs. From then on, all other outputs that happen to be in that group must also create a ring signature using the same inputs. Once the number of group ring signatures matches the number of inputs, then the entire group could be pruned from the tree all at once.
Of course I have no Idea if that works. And even if it did, there would have to be some enforced and random enough way to determine groups, otherwise a malicious actor could spend an output and create a ring signature group with outputs He wanted some kind of information on. Really just thinking out loud.
If that was possible, it would save the bloat of transmitting more transactions (although ring signatures would be larger) but pruning would be reduced since a group couldn’t be removed until all outputs in a group were spent.
I think that would improve reliability in the case of a reorg because you are drawing on transactions that are already confirmed, not potential future ones.
I’m currently reading through some monero documentation so that’s why I keep comparing these projects so much . And I’m really just a layman when it comes to understanding this stuff.
P.S. also if you draw from past transactions instead of sending zero outputs and mixing them in with future transactions that happen to pass by, you don’t have to hope that they included a large enough fee to fit your extra piece.