Lane Schwartz wrote: > I've examined the n-best lists, and it seems there are at least a > couple of interesting cases. In the simplest case, several > translations of a given sentence produce the exact same score, and > these tied translations appear in different order during different > runs. This is a bit odd, but [not] terribly worrisome. The stranger > case is when there are two different decoding runs, and for a given > sentence, there are translations that appear only in run A, and > different translations that only appear in run B.
Both these cases are relevant to something we've occasionally seen, which is non-determinism during =tuning=. This is not surprising given the above, since tuning of course involves decoding. It's hard to reproduce, but we have sometimes seen very different weights coming out of MERT for the exact same system configurations. The problem here is that even very small differences in tuning can result in substantial differences in test results, because of how twitchy BLEU is. Like many folks, we typically run MERT on a cluster. This brings up another source of non-determinism we've theorized about. Some of our clusters are heterogenous, and we've wondered if there might be minor differences in floating point behavior from machine to machine. The assignment of different chunks of the tuning data to different machines is typically non-deterministic, so this might carry over to the actual weights that come out of MERT. Does anyone know how robust the floating point usage in the decoder is under these circumstances? Thanks. - John Burger MITRE _______________________________________________ Moses-support mailing list [email protected] http://mailman.mit.edu/mailman/listinfo/moses-support
