
Chapter 7
Ad vanced Properties of
Ba y esian Net w ork
Earthquake
Alarm
Lurker
Phone Call
If Mr. Holmes’ neigh bor Dr. Watson called to report that he sees a lurker,
Mr. Holmes would reason that there probably is a lurker; therefore he might
be burglarized, which means his alarm might sound. However, if Mr. Holmes
already knew there w as a burglar as depicted above, then the phone call could
not make a burglar more likely, which means the likelihood of the alarm sound-
ing would not go up. This conditional independency, however, does n ot follow
from the statement of the Markov condition. That is, the Markov condition
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