Den 28 jan. 2017 05:04 skrev "Luke Dashjr via bitcoin-dev" <bitcoin-dev@lists.linuxfoundation.org>:

Satoshi envisioned a system where full nodes could publish proofs of invalid
blocks that would be automatically verified by SPV nodes and used to ensure
even they maintained the equivalent of full node security so long as they were
not isolated. But as a matter of fact, this vision has proven impossible, and
there is to date no viable theory on how it might be fixed. As a result, the
only way for nodes to have full-node-security is to actually be a true full
node, and therefore the plan of only having full nodes in datacenters is
simply not realistic without transforming Bitcoin into a centralised system.

Beside Zero-knowledge proofs, which is capable of proving much so more than just validity, there are multi types of fraud proofs that only rely on the format of the blocks. Such as publishing the block header + the two colliding transactions included in it (in the case of double spending), or if the syntax or logic is broken then you just publish that single transaction.

There aren't all that many cases where fraud proofs are unreasonably large for a networked system like in Bitcoin. If Zero-knowledge proofs can be applied securely, then I can't think of any exceptions at all for when the proofs would be unmanageable. (Remember that full Zero-knowledge proofs can be chained together!)