Now, wt > wtc implies, using ( 39):
γt(1 - τt-i)wt-i + (1 - γt)st ∕1 1- α ∖1-α rSt-1 iα
(40)
------->----VTi-----ʌ------- > (1 - α)(At) ʒ-
(1 - α)(1 - τt ) Nt
If γt = 1 inequality 40 becomes:
wtc <
(1 - Tt-i)wt-i _ w
(1 - α)(1 - τt)
(41)
If 0 ≤ γt < 1 solving 40 for st we obtain:
st
At '..
(42)
(1 - γt)
γthu- γf γ γt γ W( γ∏V-' Wt+ — Yt(ɪ ʃt 1)wt 1 + 0^ γt)st ?..C Tf Q, <5 Q, j^T)Pf∩ Q∩P
u ∣uSθj jj st > st we avec∙ `wt — (i α)(i τ ) > wt . ∙' st ≤ ðt enw we
have Le — Nt in which case wt — wtc. Finally we compute when st < 0. From
( 42) this inequality holds ijand only ij:
ιc < Yt(1 - τt-i)wt-i
t (1 - α)(1 - τt)
— wt .
(43)
Note from (41) and ( 43) that wt ≥ 0.
Proof of Theorem 4. 1 First we compute the best reply junction oj the union
when τt — 1 - βt. Using the proof of proposition 3.1.1 we obtain: If wtc <
w” — Yt(i-Tt-1)wt-1 then w. — Yt(i-Tt-1)wt-1+(i-Yt)st > wc IJ wc ≥ w”
w t — (i-α)βt then wt — (i-α)βt > wt . Ij wt ≥ w t
and γt — 1 then wt — wtc. If wtc ≥ w”t and 0 ≤ γt < 1 then there ex-
ists s”t — (i α)βtwt (i-Yi) τt-1)wt-1 ≥ 0 such that if st > s”t then wt —
Yt(i τt~(i-α-)β+(i Yt)st > wc and if st ≤ s” t then wt — wtc. We denote this
best reply function of the union as wt(wt-i, τt-i, 1 — βt, st, γt).
Now we compute the best reply function of the union when τt — 0. Using the
proof of proposition 3.1.1 we obtain: If wC < wt — Yt(i (i' /.)w' 1 then wt —
γt(ɪ__τt-1)wt-1 + (ɪ__γt)st /∕,c Jf /∕,c '> 7∕/ nr∣d ,y, — 1 then cιn — cnc Jf cnc γ tιd
(i α) > ɛwt. Jj ^wt ≥ 'w!t ann∣ tt — ɪ t∣ven `wt — 'w!t. Jj 'w!t ≥ 'wit
and 0 ≤ γt < 1 then there exists st — (i α)wt γtt(i τt-1)wt-1 ≥ 0 such that if
γt t (i-γt)
st > st then wt — Yt(i τt-1)W--,1)+(i Yt)st > wt and if st ≤ s't then wt — wf. We
denote this best reply function of the union as wt(wt-i,τt-i, 0, st,γt).
Functions wt(wt-i,τt-i, 1 — βt, st,γt) and wt(wt-i,τt-i, 0, st, γt) when γt —
1 and wc < wt, wt ≤ wc < w” t and w” t ≤ wc are represented in figures 1.a, 1.b
and 1.c respectively. Functions wt(wt-i, τt-i, 1—βt, st, γt) and wt(wt-i, τt-i, 0, st, γt)
when 0 ≤ γt < 1 and wc < wt, wt ≤ wc < w” t and w” t ≤ wc are represented
in figures 2.a, 2.b and 2.c respectively. On the other hand, we can also repre-
sent function st in all figures. Looking at figure 1.a it is obvious that there is a
unique equlibrium with unemployment. Looking at figure 1.b there is an equilib-
rium with unemployment and an equilibrium with full employment. Looking at
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