I have a number of questions involved here.
What is a fraudulent transaction? Is there an example of this on the blockchain?
Just to verify, in PoW the hashing algorithm is calculated to pass from one node to another and therefore there's no way that the transaction is fraudulent because otherwise the computation could not be completed, correct?
How is staking coins doing the same verification process? What is the computation that occurs that verifies the tx? Also, how could a staked node verify a fraudlulent tx and then do the really lose their coins?
Sorry for all the questions combined, but they all lead me to better understand the first question I posed in title.