At the same time that attractor basins are being drawn, the ``backwards'' space-time pattern may be displayed on the left of the screen. For basins of attraction, this will show an initial run forward, representing a transient and the attractor cycle itself (blue and grey representing 1s ad 0s). Thereafter the space-time pattern shows the information used to draw each transient tree in turn, starting from the ``root`` of the tree on the attractor, and back through successive levels in the tree. First the pre-images of the root are computed (the pre-image on the cycle is omitted), comprising level 1 in the tree. Then the pre-images of each state in level 1 are computed, comprising level 2 in the tree. This process continues through an arbitrary number of levels until all garden-of-Eden states (those without pre-images) are reached. Then the next tree is computed (note that for CA, ``compression'' allows equivalent trees to be simultaneously computed).
The ``backwards'' space-time patterns shows each state (black and grey representing 1s ad 0s) and its set of pre-images if any (red and grey representing 1s ad 0s). The scale depends on the setting in #7 in the main prompt sequence, but this may be changed ``on the fly'' (see below).
For a basin of attraction field the initial default is not to show the backward space-time patterns, and the following prompt is presented, enter ``y'' to show,
SHOW space-time patterns-y:
For a single basin or subtree, the initial default is to show the backward space-time patterns, and the following prompt is presented, enter ``n'' not to show,
NO space-time patterns-n:
Note that ``backwards'' space-time patterns can be toggled on/off while attractor basins are being drawn, and the scale can also be changed. The following reminder will appear in the bottom title bar:
STP:togg-s exp-e contr-c
Enter ``s'' to show/hide space-time patterns, ``e'' to expand the scale, ``c'' to contract the scale.