The independent-feature target-function formulation

Section 16.3. The Independent Feature Target Function Formulation... 

Two main, quite different, approaches to the target cost function have been proposed. The first, described in this section is called the independent feature formulation (IFF) and was proposed in the original Hunt and Black paper. Since then, many variations of this have been put forward but all can be described in the same general form. The second, described in Section 16.4, is termed the acoustic space formulation (ASF) and shares many similarities with the HMM systems of Chapter 15. The fact that there are only two main target function formulations is probably more due to historical accidents of system development than because these are particularly salient solutions to the problem. As we shall see, we can consider a more general formulation which encompasses both these and many other potential formulations. 

---