Routing for Lightning network: was Flare implemented? There is a 2016 paper from Bitfury on a proposed routing algorithm for LN:

Flare: An Approach to Routing
in Lightning Network

What is the relation between it and was was actually implemented (the primary reference being the BOLT specs)?
As far as I know flare was never implemented for lightning nodes and is not being used. I think current implementations use sind pathfinding algorithms like BfS or  Dijkstra. The pathfinding itself is not part of the BOLTs anyway. A node could do whatever it wants with the information provided from the gossip store / gossip protocol. (BOLT 07). People could in particular decide to go for the approach given by flare.