Consider a price taking firm with fixed costs $fc \geq 0$:
\begin{align*}
\Pi
&=
\max_{n^D} \left\{ P_c F(n^D) - w\times n^D - fc \right\}
\end{align*}
A representative household owns this firm:
$$\max_{c,n^S} U(c,n^S) \text{ s.t. } P_c c = wn^S + \Pi$$
Equilibrium: prices $(P_c, w)$ & allocations $(n^D, c, n^S)$ s.t. all optimize & markets clear:
1 (Labor market) $n^D = n^S$
2 (Goods market) $c = F(n)$
Rewrite the household's constraint:
\begin{align*}
c
&=\frac{w}{P_c} n^S + \frac{\Pi}{P_c}
\\
&=\frac{w}{P_c} n^S + F(n^D) - \frac{w}{P_c} n^D - \frac{fc}{P_c}
\tag{plug-in $\Pi$}
\\
&=\frac{w}{P_c} \left(n^S - n^D \right) + F(n^D) - \frac{fc}{P_c}
\tag{rearrange}
\\
&= F(n) - \frac{fc}{P_c} \tag{Labor Market: $n^D = n^S$}
\end{align*}
Observe the household's constraint $c = F(n) - \frac{fc}{P_c}$
is inconsistent w/ goods clearing $c = F(n)$.
Example:
$F(n)= A \log(n)$
$\Rightarrow w=\frac{P_c A}{n}
\text{ } \&\text{ } n^D(w)= A \frac{P_c}{w}
\text{ } \&\text{ } Y= A \log\left( A \frac{P_c}{w} \right)
\text{ } \&\text{ } wn = A P_c
$
$\Pi = P_c A \log\left( A \frac{P_c}{w} \right) - A P_c -fc $.
$u(c,n)=c- \frac{n^{1+\frac{1}{\varepsilon} }}{1+\frac{1}{\varepsilon}}$ s.t.
$P_c c = wn + \Pi$
$U(n)= \frac{w}{P_c} n + \frac{\Pi}{P_c}
- \frac{n^{1+\frac{1}{\varepsilon} }}{1+\frac{1}{\varepsilon}}
\Rightarrow
\frac{w}{P_c} = n^{\frac{1}{\varepsilon} }
$.
$\Rightarrow n^S(w) = \left(\frac{w}{P_c}\right)^\varepsilon
\text{ } \&\text{ } c=\left(\frac{w}{P_c}\right)^{1+\varepsilon} + \frac{\Pi}{P_c}
$
1 (Labor market) $n^D = n^S$
$\Rightarrow A \frac{P_c}{w} = \left(\frac{w}{P_c}\right)^\varepsilon
\Rightarrow A = \left(\frac{w}{P_c}\right)^{1+\varepsilon}
\Rightarrow \frac{w}{P_c} = \left(A \right)^{\frac{1}{1+\varepsilon}}
$
2 (Goods market) $c = F(n)$
$\Rightarrow
\left(\frac{w}{P_c}\right)^{1+\varepsilon} + \frac{\Pi}{P_c}
= A \log\left( A \frac{P_c}{w} \right)
$
$\Rightarrow
\left(\frac{w}{P_c}\right)^{1+\varepsilon}
+
A \log\left( A \frac{P_c}{w} \right) - A - \frac{fc}{P_c}
=
A \log\left( A \frac{P_c}{w} \right)
$
$\Rightarrow
A + \frac{fc}{P_c}
=
\left(\frac{w}{P_c}\right)^{1+\varepsilon}
\Rightarrow \frac{w}{P_c} = \left(A + \frac{fc}{P_c} \right)^{\frac{1}{1+\varepsilon}}
$
Problem:
Labor market clearing gives:
$\frac{w}{P_c} = \left(A \right)^{\frac{1}{1+\varepsilon}} $
Goods market clearing gives:
$\frac{w}{P_c} = \left(A + \frac{fc}{P_c} \right)^{\frac{1}{1+\varepsilon}} $
They are only identical if $fc=0$.
Question:
- is Walras law not supposed to hold here w/ $fc>0$ ?
- how do you set up a GE economy w/ production and fixed costs?
Attic:
We can rewrite Goods-market clearing:
$\frac{w}{P_c} n^S + \frac{\Pi}{P_c} = F(n^D)$
$
\Leftrightarrow
\frac{w}{P_c} n^S + F(n^D) - \frac{w}{P_c} n^D - \frac{fc}{P_c} = F(n^D)
$
$
\Leftrightarrow
\frac{w}{P_c} (n^S - n^D) = \frac{fc}{P_c}
$
$
\Leftrightarrow
\frac{fc}{P_c} = 0
$ if $n^D = n^S$