Also of interest are Mountain Merkle Ranges as explained here for instance: https://github.com/mimblewimble/grin/blob/master/doc/mmr.md https://github.com/mimb

Also of interest are Mountain Merkle Ranges as explained here for instance: https://github.com/mimblewimble/grin/blob/master/doc/mmr.md https://github.com/mimblewimble/grin/blob/master/doc/mmr.md These are append-only trees with height only logarithmic in number of appends.