[sirclueless]

Yes, only one block is the winner. It is whatever the maintainer of the git repository chooses as HEAD. This property is maintained by any number of out-of-band mechanisms such as Github pull requests and company-wide mandates never to "git push --force".

Seriously though, it just seems like a question of semantics. Is a blockchain just a specific sort of Merkle tree -- thus making Bitcoin a blockchain plus a distributed consensus protocol? Or does calling something a blockchain necessarily imply some consensus protocol already.

[pests]

Just semantics.

You can search right now and find programming 'blockchain tutorials', targeting the cryptocurrency community, that go on to describe only linked blocks chained together via some embedded hash of a subset of the previous blocks (meta)data. This is what others in various comments are calling a cryptograpically secured blockchain.

Other tutorials will set up a mempool (pending transactions) or get peers communicating. I've never seen peer discovery or any discussion on chain value (ie height vs accumulated difficulty) for chain selection.

[jacquesm]

> Or does calling something a blockchain necessarily imply some consensus protocol already.

It doesn't. But for all practical purposes at this point in time it might as well.