If someone were to find a Transaction Proof of Work collision, would it be possible to pin the tail of the tangle to the head and create an infinite loop?
IE. Create a self-referential tangle segment that would cause a permanent network failure?
This question assumes that a version of the IRI checks both the Hash and equality of all transactions. IE. Doesn't consider them duplicate unless they actually are.
This is a fairly theoretical question. Admittedly, it is unlikely. However, there is a non zero chance of a hash collision. Another issue might be, what would happen if one node received the one Tx1 at the same time as another node received Tx2 with the hash collision?
To stimulate the reader's imagination, here are some links that I find interesting:
How would Git handle a SHA-1 collision on a blob? https://stackoverflow.com/questions/9392365/how-would-git-handle-a-sha-1-collision-on-a-blob
Why does the IPFS project have multihashes? https://www.reddit.com/r/ipfs/comments/61r38j/hash_collision_resolution/
How does the bitcoin network recover in case of a hash collision in the block hash? https://bitcoin.stackexchange.com/questions/38384/how-does-the-bitcoin-network-recover-in-case-of-a-hash-collision-in-the-block-ha
Google's 'Announcing the first SHA1 collision' https://security.googleblog.com/2017/02/announcing-first-sha1-collision.html