The Evolution of Retirement by J. Ignacio Conde-Ruiz* Vincenzo ...
The Evolution of Retirement by J. Ignacio Conde-Ruiz* Vincenzo ...
The Evolution of Retirement by J. Ignacio Conde-Ruiz* Vincenzo ...
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∂τ t+1<br />
∂w = − δ<br />
(1 + n t+1 ) ϕ +1 + Θ<br />
s µ<br />
1 − δ(wa t+1) 2<br />
2<br />
w t+1<br />
2<br />
− 2[A−(1+r)wa t (1−τ t−δw a t )2 ]<br />
(1+n t )w t+1<br />
where<br />
Θ =<br />
Ã<br />
δ<br />
1 − δ ¡ wt+1<br />
a<br />
(1 + n t+1 ) ϕ +1<br />
¢ 2<br />
!<br />
w t+1<br />
− [(1 + n t+1) ϕ +1] £ A − (1 + r)w a t z t<br />
2 ¤<br />
(1 + n t )(w t+1 ) 2<br />
− (1 + r)z t(z t − 2δw a t )<br />
(1 + n t )w t+1<br />
Notice that we cannot sign ∂τ t+1 /∂w; however, it is easy to show that a sufficient<br />
µ<br />
condition for Θ > 0isthatA w t+1 .<br />
By eq. 12, we thus have that<br />
∂z t+1<br />
∂w<br />
δ<br />
=<br />
(1 + n t+1 ) ϕ +1 − Θ<br />
2(1+n t+1 )(w t+1 ) 2 − δ =<br />
(1 + n t+1 ) ϕ<br />
= −δ<br />
(1 + n t+1 ) ϕ +1 − Θ<br />
2(1+n t+1 )(w t+1 ) 2 < 0<br />
since Θ > 0. Q.E.D.<br />
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