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Infinitesimal Calculus of Random Walk and Poisson Processes

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Gauge Institute Journal,<br />

H. Vic Dannon<br />

(2)<br />

1<br />

EB [ ] = EB [ ] 0<br />

dt i<br />

= .<br />

(3) Var[ B] = E[ B<br />

] −( E <br />

<br />

[ B])<br />

0<br />

2 2<br />

0<br />

=<br />

=<br />

1<br />

2<br />

( dt)<br />

2<br />

( dx) 1<br />

dt<br />

dt<br />

2D<br />

2<br />

i<br />

EB [ ]<br />

,<br />

2<br />

( dx )<br />

= (2 D) δ( t ).<br />

0<br />

11.3 EB( [ ζ , t)] has unbounded Variation in [ ab ,]<br />

Pro<strong>of</strong>:<br />

2 Db− ( a) = (2 Ddt ) + (2 Ddt ) + ... + (2 Ddt )<br />

<br />

2 2<br />

( dx) ( dx) ( dx) 2<br />

⎡ 2⎤ ⎡<br />

2<br />

= E ⎢{ B(,) ζ b −B(, ζ b − dt) } ⎥ + .. + E ⎢{<br />

B(, ζ a + dt) −B(, ζ a)<br />

} ⎤ ⎥<br />

⎣ ⎦ ⎣<br />

⎦<br />

≤ max B(, ζ t + dt) −B(,) ζ t E ⎡ B(,) ζ b −B(, ζ b −dt) ⎤ ..<br />

a≤≤<br />

t b<br />

⎣<br />

⎦<br />

+<br />

<br />

infinitesimal<br />

... + max B(, ζ t + dt) − B(,) ζ t E ⎡ B(, ζ a + dt) − B(, ζ a)<br />

⎤<br />

⎣<br />

⎦<br />

=<br />

a≤≤<br />

t b<br />

= infinitesimal{ EB( ζ, b) −B( ζ, b− dt) + ... + EB( ζ, a+ dt) − B( ζ, a) },<br />

46

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