I noticed 1-2 advertisements for postdoc positions in which they provided the general description of what they want as publishing and improving the state-of-the-art in a more or less big subfield of Y. The ads. were generally asking for sending the documents without specifying what exact documents they want to receive. One of them contained something similar to
The exact subject of research depends on your personal preferences, as long as it fits this area.
So, besides sending a CV and academic transcripts, I was thinking about preparing a cover letter or a research statement (or both). The problem is that they did not specify what sort of skills they need or what specific research objectives they are interested in, so I'm afraid how to tailor my cover letter or research statement.
In fact, as the research area is of interest to me I have ideas of what sub-problems are important there and how to approach them generally. However, I do not know if they fit the group's research goals.
Also, when they did not specify, do I have to prepare both the cover letter and research statement?
BTW, I apply in Computer Science in Germany!