I have showed earlier how Bitcrust uses a Spend Tree to track the transaction graph and verify order.

I believe this same structure can also be used to tackle the difficult Fraud Proof problem by making the processing of hints indicating absent transactions, virtually free.

I propose creating a "Fraud Proof SPV" node (FSPV), by syncing this Spend Tree. It is explained here: https://bitcrust.org/blog-fraud-proofs

Please let me know what you think,

Tomas van der Wansem
Bitcrust