Neural Machine Translation of Rare Words with Subword Units
- Initialize the symbol vocabulary with all the characters plus a special ‘.’ character.
- Iteratively count all symbol pairs and merge the top pair (‘A’, ‘B’) to form a new symbol (‘AB’).
- Each merge operation produces a new symbol (in our case ‘AB’).
- The number of merge operations is the only hyper-parameter.
- The final vocabulary size is equal to number of symbols in the initial vocabulary plus the number of merge symbols.
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