Contemporary Artificial Intelligence

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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178 Chapter 7 Advanced Properties ...