where len(x) is the length in characters of text x (e.g. if the summary is 100× shorter than the source, the compression
will be 0.99). The mean compression presented in the results below is the average compression of summaries produced
by each model. We also report the standard deviation of this distribution.

3https://help.openai.com/en/articles/6654000-best-practices-for-prompt-engineering-with-openai-api

1 − len(summary)
len(source)

2

AI21 Summarize API

TECHNICAL EVALUATION

3 Results

3.1 Human evaluation
AI21 SUMMARIZE API- TECHNICAL EVALUATION