The suggestion has been made that the representation of the relationship between theoretical entities (concepts, organizations, problems, etc) could best be accomplished using methods based on graph theory, network theory and topology. The relationships registered in this project could be plotted manually as networks. However, particularly since the relationships are already coded on computer tape in a suitable format, there are three major disadvantages to this manual approach:

• graphic relationships are tiresome and time-consuming to draw, and are costly if budgeted as "art work";
• once drawn, there is a strong resistance to updating them (because of the previous point) and therefore they quickly become useless (as is frequently the case with organization charts);
• when the graph is complex, multidimensional, and carries much information, it is difficult to draw satisfactorily in two dimensions. The mass of information cannot be filtered to highlight particular features - unless yet another diagram is prepared.

These three difficulties can be overcome by making use of what is known as "interactive graphics". This is basically a television-type screen attached to a computer. The user sits at a keyboard in front of the screen and has at his disposal a "mouse" or light-pen (or some equivalent device) which allows him to point to elements of the network of concepts displayed on the screen and instruct the computer to manipulate them in useful ways. In other words the user can interact with the representation of the conceptual network using the full power of the computer to take care of the drudgery of:

• drawing in neat lines;
• making amendments;
• displaying only part of the network so that the user is not over-loaded with "relevant" information.

In effect the graphics device provides the user with a window or viewport onto the network of concepts. He can instruct the computer, via the keyboard, to:

• (a) Move the window to give him, effectively, a view onto a different part of the network - another conceptual domain;
• (b) Introduce magnification so that he can examine (or "zoom in" on) some detailed sections of the network;
• (c) Introduce diminution so that he can gain an overall view of the structure of the conceptual domain in which he is interested;
• (d) Introduce filters so that only certain types of relationships and entities are displayed - either he can switch between models or he can impose restrictions on the relationships displayed within a model, ie he has a hierarchy of filters at his disposal;
• (e) Modify parts of the network displayed to him by inserting or deleting entities and relationships. Security codes can be arranged to that (a) he can modify the display for his own immediate use without permanently affecting the basic store of data, (b) he can permanently modify features of the model for which he is a member of the responsible body, (c) and so on;
• (f) Supply text labels to features of the network which are unfamiliar to him. If necessary he can split his viewport into two (or more) parts and have the parts of the network displayed in one (or more) part(s). He can then use the light pen to point to each entity or relationship on which he wants a longer text description (eg the justifying argument for an entity or the mathematical function, if applicable, governing a relationship, and have it displayed in an adjoining viewport);
• (g) Track along the relationships between one entity and the next by moving the viewport to focus on each new entity. In this way the user moves through a representation of "semantic space" with each move, changing the constellation of entities displayed and bringing new entities and relationships into view;
• (h) Move up or down levels or "ladders of abstraction". The user can demand that the computer track the display between levels of abstraction, moving from sub-system to system, at each move bringing into view the context of the system displayed;
• (i) Distinguish between entities and relationships on the basis of user- selected characteristics. The user can have the "relevant" (to him) entities displayed with more prominent symbols, and the relevant relationships with heavier lines;
• (j) Select an alternative form of presentation. Some users may prefer block diagram flow charts, others may prefer a matrix display, others may prefer Venn diagrams (or "Venn spheres" in 3 dimensions) to illustrate the relationship between entities. These are all interconvertible (eg the Venn circles are computed taking each network node as a centre and giving a radius to include all the sub- branches of the network from that node);
• (k) Copy a particular display currently on the screen. A user may want to keep a personal record of parts of the network which are of interest to him. (He can either arrange for a dump onto a tape which can drive a graph plotter, a microfilm plotter, or copy onto a videocassette, or, in the future, obtain a direct photocopy);
• (l) Arrange for a simultaneous search through a coded microfilm to provide appropriate slide images or lengthy text (which can in its turn be photocopies);
• (m) Simulate a three-dimensional presentation of the network by introducing an extra coordinate axis;
• (n) Rotate a three-dimensional structure (about the X or Y axis) in order to heighten the 3-D effect and obtain a better view "around" the structure;
• (o) Simulate a four-dimensional presentation of the network by using various techniques for distinguishing entities and relationships (eg "flashing" relationships at frequencies corresponding to their importance in terms of the fourth dimension);
• (p) Change the speed at which the magnification from the viewport is modified as a particular structure is rotated;
• (q) Simulate the consequences of various changes introduced by the user in terms of his conditions. This is particularly useful for cybernetic displays;
• (r) Perform various analyses on particular parts of the network and display the results in a secondary viewport (eg the user might point a light-pen at an entity and request its centrality or request an indication of the interconnectedness of a particular domain delimited with the light pen.);
• (s) Use colour (when a colour screen is available) to distinguish between different concepts or networks of relationships on the same display. Several hundred colour codes are available under computer control (3);
• (t) Experiment with the generation of paths for the construction of hypothetical larger conceptual units (eg organizations) from available smaller units, as suggested by equivalent work on computer- assisted design of complex organic syntheses.