Apparatus for visualizing program slices

Apparatus for visualizing slices of transitive closures of entities having dependence relationships with one another. A preferred embodiment visualizes slices of programs. A display in a computer system includes reduced representations of the files, procedures, and lines making up a program. The user employs a pointing device to interactively select a reduced representation as the slice point and the apparatus computes the slice and changes the color of the reduced representations in the slice. The color of the reduced representation indicates the distance of the entity represented by the reduced representation from the slice point. The display may be rearranged so that files and procedures are ordered by distance from the slice point. Other aspects of the display include scaling the size of the reduced representation of a procedure to indicate the number of lines in the procedure and filling the reduced representation of the procedure according to the number of lines belonging to the slice which are contained in the procedure. A user may select open and closed representations of procedures. The open representation of a procedure contains reduced representations of the lines in the procedure. The apparatus also includes a viewer for viewing the text of lines in the program.