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GRAPHES PROBABILISTES

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…..<br />

- 60% des descendants de<br />

fumeurs sont des fumeurs,<br />

- 10% des descendants de nonfumeurs<br />

sont des fumeurs.<br />

a n + b n = 1<br />

a n+1 = p(A n+1 ) = 0.6.a n + 0.1.b n<br />

b n+1 = p(B n+1 ) = 0.4.a n + 0.9.b n<br />

A n<br />

B n<br />

0.6<br />

0.4<br />

0.1<br />

0.9<br />

( a b ) = ( a b )<br />

A n+1<br />

B n+1<br />

A n+1<br />

B n+1<br />

⎡0.<br />

6<br />

⎢<br />

0.<br />

1<br />

0.<br />

4⎤<br />

0.<br />

9<br />

n+<br />

1 n+<br />

1 n n ⎥<br />

⎣ ⎦<br />

Soit M la matrice de transition d’un graphe probabiliste et P n<br />

la matrice décrivant l’état pobabiliste à l’étape n, alors<br />

P n+1 =P n ×M et P n =P 1 ×M n-1 (si l’état initial est P 1 )

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