  In this technical report, we introduce Effidit (Efficient and Intelligent
Editing), a digital writing assistant that facilitates users to write
higher-quality text more efficiently by using artificial intelligence (AI)
technologies. Previous writing assistants typically provide the function of
error checking (to detect and correct spelling and grammatical errors) and
limited text-rewriting functionality. With the emergence of large-scale neural
language models, some systems support automatically completing a sentence or a
paragraph. In Effidit, we significantly expand the capacities of a writing
assistant by providing functions in five categories: text completion, error
checking, text polishing, keywords to sentences (K2S), and cloud input methods
(cloud IME). In the text completion category, Effidit supports generation-based
sentence completion, retrieval-based sentence completion, and phrase
completion. In contrast, many other writing assistants so far only provide one
or two of the three functions. For text polishing, we have three functions:
(context-aware) phrase polishing, sentence paraphrasing, and sentence
expansion, whereas many other writing assistants often support one or two
functions in this category. The main contents of this report include major
modules of Effidit, methods for implementing these modules, and evaluation
results of some key methods.
