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> And a 64b sweep is ~21 days

Per GPU. A consumer GPU at that (A100 is faster).

4x GPUs (the AMD 6900 XT) per node and maybe 10x nodes in a rack (4U per node, 42U cabinet) can do 64-bit sweep in half a day.

> The real issue is that the verification code is much, much, slower.

Isn't verification of 64b multipliers actually a 128-bit problem? (x * y == z, so you have 2x 64-bit numbers to work with).

Also, I think they use BDDs, which although multiplication is exponential, its still small enough exponent that 128-bit BDDs fit on today's computers. So its not a brute force thing like discussed in this topic, but actually a very elegant data-structure (though with tons of complications, as is the nature of NP-complete and expspace problems).



It’s a lot easier to do formal verification… which is a fancy BDD, in many ways.




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