BLEU
--
n-gram precision + brevity penalty
BP --
P1 --
P2 --
P3 --
P4 --
ROUGE
--
F1 of ROUGE-L (longest common subseq.)
ROUGE-1----
ROUGE-2----
ROUGE-L----
METEOR
--
unigram alignment, stemming, chunk penalty
P --
R --
pen --
Perplexity
--
char-3gram model, trained on reference · lower is better
model --
chars --