The Evolution
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than Type II intersection tasks (e.g. name a form of "blade" asso-
ciated with "hospital"), even though the only difference between the
two tasks is that Type III intersection involves intersecting two sets of
whole-to-whole links, whereas Type II intersection involves intersecting
a set of whole-to-whole links with a set of part-whole links. More will
be said on this issue later.
Memory's Need for Two Types of Links
It has up to now been assumed that evolution would force memory
to use two types of links in order to maximize its ability to anticipate
and disambiguate. What follows is a mathematical analysis of what
would happen to a memory that used only one type of link and was
therefore forced to treat Type II intersections and Type III intersections
in the same way.
Assume that the concept X occurs with an unknown probability P(X),
that Y occurs with a probability P(Y), and that the profiles emanating
from these concepts are in part as follows:
X ----------------> N
-------------------> I
Y ----------------> N
------------------> I
Assume also that P(I∣X) and P(I∣Y) are non-zero probabilities (thereby
making I, by definition, an intersected concept), that P(N∣X) equals