CCS Concepts:  $\bullet$   Computing methodologies  $\longrightarrow$  Natural language processing ;  Machine translation

1 INTRODUCTION

2 NEURAL MACHINE TRANSLATION

3 MULTIWAY NMT
3.1 Parameter Sharing
3.2 Addressing Language Divergence
3.3 Training Protocols

4 MNMT FOR LOW-RESOURCE LANGUAGE PAIRS

5 MNMT FOR UNSEEN LANGUAGE PAIRS
5.1 Pivot Translation
5.2 Zero-shot Translation
5.3 Zero-resource Translation

6 MULTI-SOURCE NMT

7 MULTILINGUALISM IN OLDER PARADIGMS
7.1 Rule-Based Machine Translation
7.2 Statistical Machine Translation

8 DATASETS AND RESOURCES

9 CONNECTIONS WITH DOMAIN ADAPTATION

10 FUTURE RESEARCH DIRECTIONS

11 CONCLUSION