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CHOOSING INVESTMENT PORTFOLIOS<br />

a-dispersion<br />

Fig.l<br />

(a) Total separation: If x0* ¥= 0, the relative proportions invested in the<br />

risky assets, namely *;*/£"=i*j*> i # 0, are independent of u and initial<br />

wealth w.<br />

(b) Partial separation: If x0* = 0, all investment is in the risky assets<br />

and £"=!*,•* = w and the x* are independent of u.<br />

Proof (a) Suppose x0* # 0. Since x* solves (2') it must satisfy the<br />

Kuhn-Tucker conditions:<br />

(i) /(*)£/*, x^O, e'x = w,<br />

(ii) (a) lt - H8fldXi) - ii

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