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October 2007 Volume 10 Number 4 - Educational Technology ...

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t ( u ), 1−<br />

f ( u )] = t ( u ), 1−<br />

f ( u )], where 1 ≤ i ≤ n.<br />

[ ~ ~<br />

A i A i<br />

[ ~<br />

B i ~<br />

B<br />

i<br />

( ~ A i u ( ~<br />

B i u<br />

That is, t ( ) = ) ( t , f ) = f ), and 1 ≤ i ≤ n. Because<br />

and<br />

~<br />

A i u<br />

~<br />

B i u<br />

( )) V S = ) (<br />

( ~<br />

A i u<br />

t – ) ( f<br />

~<br />

A i u<br />

~ A i u<br />

( ~ ( ))<br />

B i u V S = ) ( ~<br />

B i u t – ) ( ~ B i u f = ) ( ~<br />

A i u t – ) ( ~ A i u f = )). ( ( ~ A i u V S<br />

Therefore, we can see that<br />

H(Ã, B ~ ) ∑ ⎟ = ⎟<br />

n 1 ⎛ S(<br />

V ~ ( ui<br />

)) − S(<br />

V ~ ( ui<br />

)) ⎞<br />

= ⎜ A<br />

B<br />

1−<br />

n ⎜ i 1 ⎝<br />

2<br />

⎠<br />

(ii) If H(Ã, B ~ ) = 1, then<br />

= ∑ ⎟ = ⎟<br />

n 1 ⎛ S(<br />

V ~ ( ui<br />

)) − S(<br />

V ~ ( ui<br />

)) ⎞<br />

⎜ A<br />

A<br />

1−<br />

n ⎜ i 1 ⎝<br />

2<br />

⎠<br />

= 1.<br />

H(Ã, B ~ ) ∑ ⎟ = ⎟<br />

n 1 ⎛ S(<br />

V ~ ( ui<br />

)) − S(<br />

V ~ ( ui<br />

)) ⎞<br />

= ⎜ A<br />

B<br />

1−<br />

= 1.<br />

n ⎜ i 1 ⎝<br />

2<br />

⎠<br />

It implies that ( )) V S = )), ( V S where 1 ≤ i ≤ n. Because )) ( V S =<br />

( ~<br />

A i u<br />

( ( ~<br />

B i u V ( ~<br />

B i u<br />

( ~<br />

B i u ( ~ A i u<br />

( ~ B i u<br />

( ~ B i u<br />

( )) V S and S )) = t ) – f ), where 1 ≤ i ≤ n, we can see that<br />

( ~<br />

B i u<br />

t ( ) = )<br />

~<br />

A i u<br />

t and f ) = ) ( f (i.e., 1 – ) ( f = 1 – ) ( f ),<br />

~ B i u<br />

~ A i u<br />

~ B i u<br />

where 1 ≤ i ≤ n. Therefore, the vague sets à and B ~ are identical. Q. E. D.<br />

Property 4: H(Ã, B ~ ) = H( B ~ , Ã).<br />

Proof:<br />

Because<br />

H(Ã, B ~ ) ∑ ⎟ = ⎟<br />

n 1 ⎛ S(<br />

V ~ ( ui<br />

)) − S(<br />

V ~ ( ui<br />

)) ⎞<br />

= ⎜ A<br />

B<br />

1−<br />

n ⎜ i 1 ⎝<br />

2<br />

⎠<br />

and<br />

H( B ~ , Ã) ∑ ⎟ = ⎟<br />

n 1 ⎛ S(<br />

V ~ ( ui<br />

) − S(<br />

V ~ ( ui<br />

)) ⎞<br />

= ⎜ B<br />

A<br />

1−<br />

,<br />

n ⎜ i 1 ⎝<br />

2<br />

⎠<br />

and because<br />

∑<br />

=<br />

⎟ ⎟⎟<br />

⎛ ⎞<br />

1 n S(<br />

V~<br />

( u −<br />

⎜<br />

i))<br />

S(<br />

V~<br />

( ui<br />

))<br />

⎜<br />

1−<br />

A B = ∑ n i 1<br />

2<br />

⎝<br />

⎠<br />

= ⎟ ⎟⎟<br />

⎛ ⎞<br />

1 n S(<br />

V~<br />

( u −<br />

⎜<br />

i)<br />

S(<br />

V~<br />

( ui<br />

))<br />

⎜<br />

1−<br />

B A ,<br />

n i 1<br />

2<br />

⎝<br />

⎠<br />

we can see that H(Ã, B ~ ) = H( B ~ , Ã). Q. E. D.<br />

( ~ A i u<br />

229

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