Transaction finality comes from the ability to calculate cost for a double-spend such that cost exceeds the “return”–sum of all transaction amounts and any reward for mining a block (inflationary reward and/or transaction fees).
C > R
Where C is cost and R is return.
It is expected that the cost for any given block will be less than or equal to the return for the block. Hence, finality comes from an aggregation of blocks. The cost vs return increase exponentially when there is an aggregate of blocks. This is made clear in the bitcoin white-paper under section 11.
The topic I wish to discuss is how it is supposed that transaction finality can be calculated in such a system where variables pertaining to the values of C and R are unknown. To put it another way, since transaction amounts are hidden in Grin, how then can we calculate the R of a given block?
Without the ability to calculate R, how could one determine transaction finality with any level of certainty?