HMM: decoding
WGP ARQLNES VKDINKM LER HP
BBB CCCCCCC CCCCCCC CCC BB
000 abcdefg abcdefg abc 00
00c defgabc defgabc def g0
VITERBI decoding: of all possible state-paths, we determine the maximum probability one given the amino acid sequence O;
POSTERIOR decoding: at each position, we determine the state with the highest probability given O.