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M. Tirelli
show that this property holds we can proceed by appending
(b 1 ,...,bH)KZ = 0,
bbT - 1 = 0
to the equilibrium system, F = 0, and show that the new system as no
solution at tI = 0 (for this we need that H ≤ S - J). This property is
implied by the well-known property of local controllability of individual
state prices, λ. Thus, restrict attention to the set Ψ* for which Theorem 2
in Geanakoplos et al. (1990) holds, and (i) through (iv) are satisfied; these
properties can be shown to hold generically in consumers’ endowments, e.
Observe that, at t1 = 0, F and the system of first-order GEI equilibrium
conditions, F, are identical, and that so are their Jacobians with respect to
ξ '. Therefore,
rank (Dξ,F(ξ,, tI, ψ) |f(ξ,,ti,ψ)=o)t, =0 = n,,
and the set of regular equilibria, F -1 (0), is a manifold of dimension k =
dim(Ψ). Next, we add the government budget constraint to F to get F,
the complete system of first-order conditions of the E - tI equilibrium.
We want to show that the Jacobian of F , evaluated at a no-tax equilibrium,
has full rank. Now (Dξ,,tι F F(ξ,,tι,ψ*=0)tI=0 has the following structure (its
complete representation is in (5) below, with the last column and row blocks
deleted):
var. ξ, t1
equ. ---------
F | Dξ, F ..........
n ,× n,
∑ h ∈ H ( tS + tS (∑ j ∈ J, θhRj + ∑ ∈ J2 θj )) = 0 | 0 [∑j ∈ J2 yj ] ( * *
S×S
(*) : [ξs]denotes a block-diagonal matrix with typical element ξs.
Since we take ψ ∈ Ψ*, we have that ∑j-ysj = 0 for all s. Thus, if0is a
regular value of F, it is also a regular value of F. □
By straightforward application of the implicit function theorem, we ob-
tain the following.
Corollary 2. In the context of Theorem 2, for every ψ ∈ Ψ *, there exists an
open neighborhood N (0) of ti = 0 such that, for all ti ∈ N (0),
rank (Dξ,,tiF(ξ,, t1, ψ) |F(ξ,,ti,ψ*=o) = n,
and F(ξ,, t1, ψ) is transverse to zero.