In the paper, Eligibility Traces for off-Policy Policy Evaluation (2010), by Doina Precup et al., mentioned the term "non-starving" many times. The specific use of the term was like "non-starving policy" in the context of off-policy learning.
A specific mention of the term
we consider a method that requires nothing of the behavior policy other than that it be non-starving, i.e., that it never reaches a time when some state-action pair is never visited again.
What does the thing look like intuitively? Why is it required?