  Stack Overflow (SO) has become an essential resource for software
development. Despite its success and prevalence, navigating SO remains a
challenge. Ideally, SO users could benefit from highlighted navigational cues
that help them decide if an answer is relevant to their task and context. Such
navigational cues could be in the form of essential sentences that help the
searcher decide whether they want to read the answer or skip over it. In this
paper, we compare four potential approaches for identifying essential
sentences. We adopt two existing approaches and develop two new approaches
based on the idea that contextual information in a sentence (e.g., "if using
windows") could help identify essential sentences. We compare the four
techniques using a survey of 43 participants. Our participants indicate that it
is not always easy to figure out what the best solution for their specific
problem is, given the options, and that they would indeed like to easily spot
contextual information that may narrow down the search. Our quantitative
comparison of the techniques shows that there is no single technique sufficient
for identifying essential sentences that can serve as navigational cues, while
our qualitative analysis shows that participants valued explanations and
specific conditions, and did not value filler sentences or speculations. Our
work sheds light on the importance of navigational cues, and our findings can
be used to guide future research to find the best combination of techniques to
identify such cues.
