What long-term technical goals will this work serve?
What are the main barriers to progress? What has led to success so far and what limitations remain? What is the missing knowledge?
What aspects of the current state-of-the-art lead to this proposal? Why are these the right issues to be addressing now?
"What lessons from past and current research motivate your work. What value will your research provide? What is it that your results will make possible?
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What is the relation to the present state of knowledge, to current work here & elsewhere? Cite those whose work you're building on. Don't insult anyone. For example, don't say their work is "inadequate;" rather, identify the issues they didn't