Based on the definition of a logic structure feature to relate logically functional requirements to geometric representation independent upon detailed geometric representation, this paper presents an idea of logical structure modeling for computer aided conceptual design and makes attempt to establish a representation formalism of logic structure modeling.

In this paper,we give a description of formal representation of HTN problem and its operational semantics,then analyse the complexity of HTN and point out the strong and weak points in HTN planning technology.

The rational Bézier representation for quadratic curve and its transition;