http://monerotoruzizulg5ttgat2emf4d6fbmiea25detrmmy7erypseyteyd.onion/2018/12/03/logs-for-the-Monero-Research-Lab-meeting-held-on-2018-12-03.html
<sarang> Proposals around refund transactions can take advantage of that new construction, but not with this proposal <h4sh3d> In this scheme the first XMR transaction move funds into the address controlled w/ (a,x) private key, where x is half controlled by Alice and half by Bob <sarang> OK, if Bob disappears, Alice can recover the key?