Tamarin is a hybrid permissioned/permissionless layer 2 blockchain technology which enables consortiums of organisations to store and execute smart contracts on a permissioned layer while rooting the state of execution to permissionless systems. See roadmap here: https://syscoin.community/data/docs/roadmap_syscoin_nov.pdf
Tamarin by Blockchain Foundry
Redrace
#2
Further explanation on Tamarin in this AMA:
https://syscoin.community/articles/dantime-23-november