Page 197 - Applied Probability

9. Descent Graph Methods
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FIGURE 9.4. Example of Transition Rule T 1
person i and a locus l. It then performs a T 0 transition at each node deter-
mined by a child of i, the given locus l, and the sex of i. Thus, every child
of i who previously inherited i’s maternal gene now inherits i’s paternal
gene and vice versa.

Transition Rule T 2a

Transition Rule T 2b
FIGURE 9.5. Examples of Transition Rules T 2a and T 2b
Our second composite transition rule has the two variants T 2a and T 2b
illustrated in Figure 9.5. Each variant begins by choosing a locus l and
a couple i and j with common children. Four different descent subtrees
are rooted at the parents i and j. In Figure 9.5 these start at the black
nodes. Rule T 2a exchanges the subtree rooted at the maternal node of i
with the subtree rooted at the maternal node of j; it likewise exchanges
the paternally rooted subtrees of i and j. In contrast, rule T 2b exchanges
the maternally rooted subtree of i with the paternally rooted subtree of j