On minimal Poincar\'{e} 4-complexes

We consider two types of minimal Poincar\'e $4$-complexes. One is defined with respect to the degree $1$-map order. This idea was already present in our previous papers, and more systematically studied later by Hillman. The second type of minimal Poincar\'e $4$-complexes were introduced by Hambleton, Kreck and Teichner. It is not based on an order relation. In the present paper we study existence and uniqueness.