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View Carlson-Titman-Tiu Paper - The Paul Merage School of Business

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V R (r, L) = V P (r, L) + cP RL. (28)<br />

<strong>The</strong> third possibility is that it is optimal to have had no switches at the current time. In this<br />

case, for a small enough θ, Iθ = R and there are no switching costs being paid between 0 and θ,<br />

i.e.,<br />

<br />

τn≤θ<br />

e − τn<br />

0 Rs(Is)ds ckn−1, kn Lτn = 0.<br />

Dividing by θ in (26), and pushing θ to zero, we have:<br />

V<br />

lim<br />

θ→0<br />

R − exp(− θ Iθ<br />

0 Rsds)V<br />

θ<br />

θ<br />

1 − exp(− 0 = lim<br />

θ→0<br />

Rsds)<br />

<br />

V<br />

θ<br />

R ,<br />

where the equal sign follows because it is suboptimal to change type before time θ. <strong>The</strong> above limit<br />

is further equal to<br />

We also have that<br />

and that<br />

<strong>The</strong>refore, if switching is suboptimal,<br />

This equation can be rewritten as:<br />

V R θ<br />

lim Rθ(r) exp(−<br />

θ→0 0<br />

Rsds) = rV R (r, L).<br />

lim<br />

θ→0 −e− θ<br />

0 Rsds<br />

θ<br />

0 LV Iθdt<br />

= −LV<br />

θ<br />

R (r, L)<br />

−<br />

lim<br />

θ→0<br />

θ<br />

0 e− t<br />

0 RsdsLtdt = −l.<br />

θ<br />

rV R − LV R − L = 0. (29)<br />

−(1/2)σ 2 rV R<br />

rr − ρσrσLLV R<br />

rL − (1/2)σ2 L L2 V R LL<br />

−µrV R<br />

r − µLLV R L + r∗ V R − L = 0.<br />

We can look for a solution <strong>of</strong> the form V R (r, L) = LφR(r), and substituting in (30) we observe that<br />

φ R satisfies:<br />

20<br />

(30)

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