Showing papers on "Constraint graph (layout) published in 1986"
02 Jul 1986
TL;DR: This approach provides a general and rigorous method for wire-length minimization and includes a graph-theoretic Simplex method that can be used to solve minimization problems whose constraints can be expressed in terms of a directed graph.
Abstract: This paper presents a graph-theoretic compactor that minimizes the areas of the bounding rectangle and the individual rectangles in the layout. The minimization problem is formulated as a two-stage process. In the first stage, the area of the bounding rectangle is minimized, and in the second stage, the weighted sum of the areas of the individual rectangles is minimized, which automatically minimizes the lengths of the inter-connecting wires. This approach provides a general and rigorous method for wire-length minimization. Algorithms for generating and solving the constraint graph are proposed. The minimization algorithm includes a graph-theoretic Simplex method that can be used to solve minimization problems whose constraints can be expressed in terms of a directed graph.
43 citations
02 Jul 1986
TL;DR: Flute is a heuristic floorplanner that operates as one of the agents of the Cadre - a system of cooperating expert agents for converting a hierarchical structural description into full custom VLSI layout.
Abstract: Flute is a heuristic floorplanner that operates as one of the agents of the Cadre - a system of cooperating expert agents for converting a hierarchical structural description into full custom VLSI layout. Flute is modeled on the human floorplanning process and uses a mixture of rule-based programming, state control and algorithmic operators. Initially, a topological plan is generated by placing modules on a grid graph. From this plan, a constraint graph is prepared. This graph is solved in order to add geometric size and placement information to the floorplan.
14 citations
TL;DR: This letter examines channels with two-terminal nets without doglegging and assumes that some terminals are interchangeable, and shows the routability condition is shown to be weaker if noninter-changeable points have different abscissas.
Abstract: The traditional channel routing problem is known to be solvable, if and only if the constraint graph is acyclic. In the letter we examine channels with two-terminal nets without doglegging and assume that some terminals are interchangeable. A necessary and sufficient condition is established for the interchangeability of the points to ensure solvability. Regular channel structures, like those in gate arrays, are compared. The routability condition is shown to be weaker if noninter-changeable points have different abscissas.