This volume is both a tribute to Ulrich Felgner's research inalgebra, logic, and set theory and a strong researchcontribution to these areas. Felgner's former students, friendsand collaborators have contributed sixteen papers to thisvolume that highlight the unity of these three fields in the spiritof Ulrich Felgner's own research. The interested reader will find excellent original research surveys and papers that span the field from set theory without the axiom of choice via model-theoretic algebra to the mathematics of intonation.