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[money_inflation] updated steady state (#497)
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Dear John @jstac ,

This pull request finishes the issue #437 .

Best,
Longye
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longye-tian authored Jul 1, 2024
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Expand Up @@ -170,7 +170,7 @@ We shall describe two distinct but closely related ways of computing a pair $\
But first it is instructive to describe a special type of equilibrium known as a **steady state**.
In a steady state equilibrium, a subset of key variables remain constant or **invariant** over time, while remaining variables can be expressed as functions of those constant variables.
In a steady-state equilibrium, a subset of key variables remain constant or **invariant** over time, while remaining variables can be expressed as functions of those constant variables.
Finding such state variables is something of an art.
Expand All @@ -180,7 +180,7 @@ This is true in the present model.
### Steady states
In a **steady state** equilibrium of the model we are studying,
In a steady-state equilibrium of the model we are studying,
$$
\begin{aligned}
Expand Down Expand Up @@ -229,7 +229,7 @@ $$
R_t \in [\underline R, \overline R], \quad t \geq 0.
$$
Maximizing steady state seigniorage {eq}`eq:SSsigng` with respect to $\bar R$, we find that the maximizing rate of return on currency is
Maximizing steady-state seigniorage {eq}`eq:SSsigng` with respect to $\bar R$, we find that the maximizing rate of return on currency is
$$
\bar R_{\rm max} = \sqrt{\frac{\gamma_2}{\gamma_1}}
Expand Down Expand Up @@ -263,7 +263,7 @@ plt.rcParams['figure.dpi'] = 300
from collections import namedtuple
```
Let's set some parameter values and compute possible steady state rates of return on currency $\bar R$, the seigniorage maximizing rate of return on currency, and an object that we'll discuss later, namely, an initial price level $p_0$ associated with the maximum steady state rate of return on currency.
Let's set some parameter values and compute possible steady-state rates of return on currency $\bar R$, the seigniorage maximizing rate of return on currency, and an object that we'll discuss later, namely, an initial price level $p_0$ associated with the maximum steady-state rate of return on currency.
First, we create a `namedtuple` to store parameters so that we can reuse this `namedtuple` in our functions throughout this lecture
Expand Down Expand Up @@ -337,7 +337,7 @@ plt.show()
Let's print the two steady-state rates of return $\bar R$ and the associated seigniorage revenues that the government collects.
(By construction, both steady state rates of return should raise the same amounts real revenue.)
(By construction, both steady-state rates of return should raise the same amounts real revenue.)
We hope that the following code will confirm this.
Expand All @@ -349,7 +349,7 @@ g2 = seign(msm.R_l, msm)
print(f'R_l, g_l = {msm.R_l:.4f}, {g2:.4f}')
```
Now let's compute the maximum steady state amount of seigniorage that could be gathered by printing money and the state state rate of return on money that attains it.
Now let's compute the maximum steady-state amount of seigniorage that could be gathered by printing money and the state state rate of return on money that attains it.
## Two computation strategies
Expand Down Expand Up @@ -434,7 +434,7 @@ As we shall see soon, selecting an initial $p_0$ in method 2 is intimately tied
%b_0 = \gamma_1 - \gamma_0 R_0^{-1}
%$$

Remember that there exist two steady state equilibrium values $ R_\ell < R_u$ of the rate of return on currency $R_t$.
Remember that there exist two steady-state equilibrium values $ R_\ell < R_u$ of the rate of return on currency $R_t$.

We proceed as follows.

Expand All @@ -460,7 +460,7 @@ condition $R_0$.

The quantity $1 - R_t$ can be interpreted as an **inflation tax rate** that the government imposes on holders of its currency.

We shall soon see that the existence of two steady state rates of return on currency
We shall soon see that the existence of two steady-state rates of return on currency
that serve to finance the government deficit of $g$ indicates the presence of a **Laffer curve** in the inflation tax rate.

```{note}
Expand Down Expand Up @@ -746,7 +746,7 @@ y^*_{t+1} = \Lambda^t y^*_t .
$$ (eq:stardynamics)
This equation represents the dynamics of our system in a way that lets us isolate the
force that causes gross inflation to converge to the inverse of the lower steady state rate
force that causes gross inflation to converge to the inverse of the lower steady-state rate
of inflation $R_\ell$ that we discovered earlier.
Staring at equation {eq}`eq:stardynamics` indicates that unless
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