tá a babá tá a babá
tá a babá tá a babá .
t a WORD_BOUNDARY a WORD_BOUNDARY β a β a WORD_BOUNDARY t a WORD_BOUNDARY a WORD_BOUNDARY β a β a WORD_BOUNDARY
t á WORD_BOUNDARY a WORD_BOUNDARY b a b á WORD_BOUNDARY t á WORD_BOUNDARY a WORD_BOUNDARY b a b á WORD_BOUNDARY . WORD_BOUNDARY