Mathematicians have long recognized the distinction between an argument showing that an interesting object exists and a procedure for actually constructing the object. Computer science adds a new dimension of interest in constructivity, since a computer program is a formal description of a constructive procedure that can be executed automatically. It has beenover a decade since a conference was devoted to constructivity, and never before has one been held specifically relating computer science to constructivity. Thus, this proceedings volume is the most concentrated offering ever produced of...