* add MMI to AIShell * fix MMI decode graph * export model * typo * fix code style * typo
* Add aishell recipe * Remove unnecessary code and update docs * adapt to k2 v1.7, add docs and results * Update conformer ctc model * Update docs, pretrained.py & results * Fix code style * Fix code style * Fix code style * Minor fix * Minor fix * Fix pretrained.py * Update pretrained model & corresponding docs