The purpose of this section is to discuss current approaches that describe parsing and generation under a uniform approach but explicitly taking into account efficiency and effectivity considerations. According to the classification schema specified in section 2.2 we are basically interested in approaches that belong to type D, i.e., we do not explicitly consider approaches that rely on compilation, e.g. like the one described in [Dymetman et al. 1990, Strzalkowski1989, Block1991]. The main reasons of considering only truly uniform approaches in detail are that they fulfill the criterion of economy and that only for them it makes sense to develop the new item sharing approach which is necessary for achieving an efficient and practical interleaving of parsing and generation.
We also do not consider approaches, that describe alternative approaches of uniform processing, for example, the view of parsing and generation as type inference (see e.g., [Emele and Zajac1990]) or the use of synchronous tree-adjoining grammars (see [Shieber and Schabes1990]), but only under a formal or principle aspect because this would exceed the scope of this work.