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Issue No.02 - April (1993 vol.5)
pp: 352-362
ABSTRACT
<p>A paradigm is proposed for representing hierarchically specified design data in CAD database systems in which there are alternate expansions of hierarchically specified modules. The paradigm uses an ancestor-based scheme to control which instances of submodules are to be placed in the expansion of each instance of a given module and is formalized using a versioned directed acyclic multigraph (VDAG). The approach is aimed at reducing storage space in engineering design database systems and at providing a means for designers to specify alternate expansions of a module. The VDAG model is defined, and a mechanism by which a VDAG generates an exploded forest of design trees is described. Algorithms are provided to generate a design forest from a given VDAG, determine whether one module is contained by a larger module, extract a version from a VDAG, test whether two VDAGs are equivalent, and try to reduce the size of a VDAG. The problems of module containment and VDAG inequivalence are shown to be NP-complete, and the problem of finding a minimum sized VDAG equivalent to a given VDAG is shown to be NP-hard.</p>
INDEX TERMS
hierarchically specified design data; CAD database systems; hierarchically specified modules; ancestor-based scheme; versioned directed acyclic multigraph; VDAG; engineering design database systems; exploded forest; design trees; VDAG inequivalence; NP-complete; minimum sized VDAG; CAD; database management systems; graph theory
CITATION
L. Yu, D.J. Rosenkrantz, "Ancestor Controlled Submodule Inclusion in Design Databases", IEEE Transactions on Knowledge & Data Engineering, vol.5, no. 2, pp. 352-362, April 1993, doi:10.1109/69.219741
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