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68 CHAPTER 5. ND-SYSTEMS APPROACH IN POLYNOMIAL OPTIMIZATION<br />

between a point of <strong>to</strong>tal time k and nearby points of <strong>to</strong>tal time k − 1. (Alternatively,<br />

one may construct minimal stable patterns by deleting points from a stable pattern<br />

of the form N until stability is lost.)<br />

In Figure 5.7 it is shown for the case n = 3 and m = 2 how the points with<br />

<strong>to</strong>tal time 4 (blue layer, Figure b) are connected along the directions of the time axes<br />

(red lines) <strong>to</strong> nearby points of <strong>to</strong>tal time 3 (green layer, Figure a). In Figure 5.8b<br />

the points in these two consecutive layers are arranged in convenient triangulated<br />

patterns and shown from two different viewpoints (of which the last one will be used<br />

in the following).<br />

(a)<br />

(b)<br />

Figure 5.7: (a) Points with <strong>to</strong>tal time 4. (b) Connections of the points with <strong>to</strong>tal<br />

time 4 <strong>to</strong> nearby points of <strong>to</strong>tal time 3<br />

In Figure 5.9 it is visualized how the three different full recursions associated with<br />

f (1) , f (2) and f (3) may assist in the computation of a point with <strong>to</strong>tal time 4, and<br />

also which points of <strong>to</strong>tal time 3 (red triangle) are required <strong>to</strong> achieve this.<br />

For n = 3 and m = 2, the stable pattern N in the previous proposition has 10<br />

points. When two of its corner points are deleted, a minimal stable pattern of 8<br />

points remains, which however allows only for a shift in just one of the directions of<br />

the time axes. But when only one corner point is deleted, a stable pattern results<br />

which allows for shifts in all three directions of the time axes.<br />

As a consequence, a solution <strong>to</strong> the RSPP needs <strong>to</strong> take in<strong>to</strong> account the coordinate<br />

values of the time instant t =(t 1 ,t 2 ,t 3 ) associated with the terminal node v T . First,<br />

a stable pattern containing 9 points can be used for shifting along the two axes<br />

corresponding <strong>to</strong> the two smallest values of t 1 , t 2 , and t 3 . Then a cheaper minimal<br />

stable pattern containing 8 points can be used for shifting along the remaining third<br />

axis (this should be a subpattern of the previous pattern of 9 points). Note that such

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