Orlik has been working in the area of arrangements for thirty years. Lectures on this subject include CBMS Lectures in Flagstaff, AZ; Swiss Seminar Lectures in Bern, Switzerland; and Summer School Lectures in Nordfjordeid, Norway, in addition to many invited lectures, including an AMS hour talk.
Welker works in algebraic and geometric combinatorics, discrete geometry and combinatorial commutative algebra. Lectures on the topic of the book include Summer School on Topological Combinatorics, Vienna and Summer School Lectures in Nordfjordeid, in addition to several invited talks.