"""
General Equilibrium Model for Korea (KORCNS)
This mini equilibrium model of Korea for the year 1963 is used to
illustrate the basic use of CGE models. This version follows closely
Chapter 11 of the reference.
The original model (KORCGE) is formulated as an optimization
model, but it is really a square system of nonlinear equations.
In this version, we formulate the model directly as a square system
using the model type CNS = Constrained Nonlinear System.
An MCP version exist under the name (KORMCP).
Lewis, J, and Robinson, S, Chapter 11. In Chenery, H B, Robinson, S,
and Syrquin, S, Eds, Industrialization and Growth: A Comparative
Study. Oxford University Press, London, 1986.
Keywords: constrained nonlinear system, general equilibrium model, economic
growth,
industrialization, economic policy, Korean economy
"""
from __future__ import annotations
import os
import numpy as np
import pandas as pd
from gamspy import Alias
from gamspy import Container
from gamspy import Equation
from gamspy import Model
from gamspy import Number
from gamspy import Parameter
from gamspy import Product
from gamspy import Set
from gamspy import Sum
from gamspy import Variable
def main():
# Data
data = [
[0.00000, 0.00000, 0.00000],
[0.01000, 0.03920, 0.05000],
[0.02000, 0.07000, 0.91000],
[0.13000, 0.29000, 0.58000],
[0.00000, 0.00000, 0.00000],
[0.00000, 0.00000, 0.00000],
[0.10000, 0.22751, 0.08084],
[0.61447, 1.60111, 0.52019],
[0.33263, 0.43486, 0.23251],
[0.90909, 0.81466, 0.92521],
[1.00000, 1.00000, 1.00000],
[2.00000, 0.66000, 0.40000],
[0.24820, 0.05111, 0.00001],
[1.59539, 1.34652, 1.01839],
[2.00000, 2.00000, 2.00000],
[0.86628, 0.84602, 0.82436],
[3.85424, 3.51886, 3.23592],
]
columns = ["agricult", "industry", "services"]
indexes = [
"depr",
"itax",
"gles",
"kio",
"dstr",
"te",
"tm",
"ad",
"pwts",
"pwm",
"pwe",
"sigc",
"delta",
"ac",
"sigt",
"gamma",
"at",
]
zz_df = pd.DataFrame(data=data, columns=columns, index=indexes)
zz_df = zz_df.reset_index().melt(
id_vars="index", var_name="Category", value_name="Value"
)
# sectres
data = [
[1.0000, 1.0000, 1.0000],
[1.0000, 1.0000, 1.0000],
[0.7370, 0.2911, 0.6625],
[711.6443, 930.3509, 497.4428],
[657.3677, 840.0500, 515.4296],
[641.7037, 812.2222, 492.0307],
[15.6639, 27.8278, 23.3988],
[69.9406, 118.1287, 5.4120],
[657.5754, 338.7076, 1548.5192],
[256.6450, 464.1656, 156.2598],
[452.1765, 307.8561, 202.0416],
[2.8230, 9.8806, 128.4482],
[0.0000, 148.4488, 10.6931],
[0.0000, 0.0000, 0.0000],
[20.6884, 46.1511, 92.3023],
[1.0000, 1.0000, 1.0000],
[1.0000, 1.0000, 1.0000],
[1.0000, 1.0000, 1.0000],
[1.0000, 1.0000, 1.0000],
]
columns = ["agricult", "industry", "services"]
indexes = [
"pd1",
"pk",
"pva",
"x",
"xd",
"xxd",
"e",
"m",
"k",
"intr",
"cd",
"gd",
"id",
"dst",
"dk",
"pm",
"pe",
"px",
"p",
]
sectres_df = pd.DataFrame(data=data, columns=columns, index=indexes)
sectres_df = sectres_df.reset_index().melt(
id_vars="index", var_name="Category", value_name="Value"
)
# Model's container
cont = Container(
delayed_execution=int(os.getenv("DELAYED_EXECUTION", False))
)
# Sets
i = Set(cont, name="i", records=["agricult", "industry", "services"])
hh = Set(cont, name="hh", records=["lab_hh", "cap_hh"])
lc = Set(cont, name="lc", records=["labor1", "labor2", "labor3"])
it = Set(cont, name="it", domain=[i])
inn = Set(cont, name="inn", domain=[i])
j = Alias(cont, name="j", alias_with=i)
# Parameters
delta = Parameter(cont, name="delta", domain=[i])
ac = Parameter(cont, name="ac", domain=[i])
rhoc = Parameter(cont, name="rhoc", domain=[i])
rhot = Parameter(cont, name="rhot", domain=[i])
at = Parameter(cont, name="at", domain=[i])
gamma = Parameter(cont, name="gamma", domain=[i])
ad = Parameter(cont, name="ad", domain=[i])
gles = Parameter(cont, name="gles", domain=[i])
depr = Parameter(cont, name="depr", domain=[i])
dstr = Parameter(cont, name="dstr", domain=[i])
kio = Parameter(cont, name="kio", domain=[i])
te = Parameter(cont, name="te", domain=[i])
itax = Parameter(cont, name="itax", domain=[i])
htax = Parameter(cont, name="htax", domain=[hh])
pwm = Parameter(cont, name="pwm", domain=[i])
pwe = Parameter(cont, name="pwe", domain=[i])
tm = Parameter(cont, name="tm", domain=[i])
pwts = Parameter(cont, name="pwts", domain=[i])
htax["lab_hh"] = 0.08910
htax["cap_hh"] = 0.08910
alphl = Parameter(
cont,
name="alphl",
domain=[i, lc],
records=np.array(
[
[0.38258, 0.06740, 0.00000],
[0.00000, 0.53476, 0.00000],
[0.00000, 0.16234, 0.42326],
]
),
)
io = Parameter(
cont,
name="io",
domain=[i, j],
records=np.array(
[
[0.12591, 0.19834, 0.01407],
[0.10353, 0.35524, 0.18954],
[0.02358, 0.11608, 0.08390],
]
),
)
imat = Parameter(
cont,
name="imat",
domain=[i, j],
records=np.array(
[
[0.00000, 0.00000, 0.00000],
[0.93076, 0.93774, 0.93080],
[0.06924, 0.06226, 0.06920],
]
),
)
wdist = Parameter(
cont,
name="wdist",
domain=[i, lc],
records=np.array(
[
[1.00000, 0.52780, 0.00000],
[0.00000, 1.21879, 0.00000],
[0.00000, 1.11541, 1.00000],
]
),
)
cles = Parameter(
cont,
name="cles",
domain=[i, hh],
records=np.array(
[[0.47000, 0.47000], [0.31999, 0.31999], [0.21001, 0.21001]]
),
)
zz = Parameter(cont, name="zz", domain=["*", i], records=zz_df)
depr[i] = zz["depr", i]
itax[i] = zz["itax", i]
gles[i] = zz["gles", i]
kio[i] = zz["kio", i]
dstr[i] = zz["dstr", i]
te[i] = zz["te", i]
tm[i] = zz["tm", i]
ad[i] = zz["ad", i]
pwts[i] = zz["pwts", i]
pwm[i] = zz["pwm", i]
pwe[i] = zz["pwe", i]
rhoc[i] = (1 / zz["sigc", i]) - 1
delta[i] = zz["delta", i]
ac[i] = zz["ac", i]
rhot[i] = (1 / zz["sigt", i]) + 1
gamma[i] = zz["gamma", i]
at[i] = zz["at", i]
# Model Definition
# Variables
# prices block
er = Variable(cont, name="er", type="free")
pd1 = Variable(cont, name="pd1", type="free", domain=[i])
pm = Variable(cont, name="pm", type="free", domain=[i])
pe = Variable(cont, name="pe", type="free", domain=[i])
pk = Variable(cont, name="pk", type="free", domain=[i])
px = Variable(cont, name="px", type="free", domain=[i])
p = Variable(cont, name="p", type="free", domain=[i])
pva = Variable(cont, name="pva", type="free", domain=[i])
pr = Variable(cont, name="pr", type="free")
pindex = Variable(cont, name="pindex", type="free")
# production block
x = Variable(cont, name="x", type="free", domain=[i])
xd = Variable(cont, name="xd", type="free", domain=[i])
xxd = Variable(cont, name="xxd", type="free", domain=[i])
e = Variable(cont, name="e", type="free", domain=[i])
m = Variable(cont, name="m", type="free", domain=[i])
# factors block
k = Variable(cont, name="k", type="free", domain=[i])
wa = Variable(cont, name="wa", type="free", domain=[lc])
ls = Variable(cont, name="ls", type="free", domain=[lc])
l = Variable(cont, name="l", type="free", domain=[i, lc])
# demand block
intr = Variable(cont, name="intr", type="free", domain=[i])
cd = Variable(cont, name="cd", type="free", domain=[i])
gd = Variable(cont, name="gd", type="free", domain=[i])
id = Variable(cont, name="id", type="free", domain=[i])
dst = Variable(cont, name="dst", type="free", domain=[i])
y = Variable(cont, name="y", type="free")
gr = Variable(cont, name="gr", type="free")
tariff = Variable(cont, name="tariff", type="free")
indtax = Variable(cont, name="indtax", type="free")
netsub = Variable(cont, name="netsub", type="free")
gdtot = Variable(cont, name="gdtot", type="free")
hhsav = Variable(cont, name="hhsav", type="free")
govsav = Variable(cont, name="govsav", type="free")
deprecia = Variable(cont, name="deprecia", type="free")
invest = Variable(cont, name="invest", type="free")
savings = Variable(cont, name="savings", type="free")
mps = Variable(cont, name="mps", type="free", domain=[hh])
fsav = Variable(cont, name="fsav", type="free")
dk = Variable(cont, name="dk", type="free", domain=[i])
ypr = Variable(cont, name="ypr", type="free")
remit = Variable(cont, name="remit", type="free")
fbor = Variable(cont, name="fbor", type="free")
yh = Variable(cont, name="yh", type="free", domain=[hh])
tothhtax = Variable(cont, name="tothhtax", type="free")
# welfare indicator for objective function
omega = Variable(cont, name="omega", type="free")
er.l[...] = 1.0000
pr.l[...] = 0.0000
pindex.l[...] = 1.0000
gr.l[...] = 194.0449
tariff.l[...] = 28.6572
indtax.l[...] = 65.2754
netsub.l[...] = 0.0000
gdtot.l[...] = 141.1519
hhsav.l[...] = 61.4089
govsav.l[...] = 52.8930
deprecia.l[...] = 0.0000
savings.l[...] = 159.1419
invest.l[...] = 159.1419
fsav.l[...] = 39.1744
fbor.l[...] = 58.7590
remit.l[...] = 0.0000
tothhtax.l[...] = 100.1122
y.l[...] = 1123.5941
labres1 = Parameter(
cont,
name="labres1",
domain=[i, lc],
records=np.array(
[
[2515.900, 442.643, 0.000],
[0.000, 767.776, 0.000],
[0.000, 355.568, 948.100],
]
),
)
labres2 = Parameter(
cont,
name="labres2",
domain=["*", lc],
records=pd.DataFrame(
[
["wa", "labor1", 0.074],
["ls", "labor1", 2515.9],
["wa", "labor2", 0.14],
["ls", "labor2", 1565.987],
["wa", "labor3", 0.152],
["ls", "labor3", 948.1],
]
),
)
hhres = Parameter(
cont,
name="hhres",
domain=["*", hh],
records=pd.DataFrame(
[
["yh", "lab_hh", 548.7478],
["mps", "lab_hh", 0.06],
["yh", "cap_hh", 574.8463],
["mps", "cap_hh", 0.06],
]
),
)
l.l[i, lc] = labres1[i, lc]
ls.l[lc] = labres2["ls", lc]
wa.l[lc] = labres2["wa", lc]
mps.l[hh] = hhres["mps", hh]
yh.l[hh] = hhres["yh", hh]
sectres = Parameter(
cont, name="sectres", domain=["*", i], records=sectres_df
)
pd1.l[i] = sectres["pd1", i]
pm.l[i] = sectres["pm", i]
pe.l[i] = sectres["pe", i]
pk.l[i] = sectres["pk", i]
px.l[i] = sectres["px", i]
p.l[i] = sectres["p", i]
pva.l[i] = sectres["pva", i]
x.l[i] = sectres["x", i]
xd.l[i] = sectres["xd", i]
xxd.l[i] = sectres["xxd", i]
e.l[i] = sectres["e", i]
m.l[i] = sectres["m", i]
k.l[i] = sectres["k", i]
intr.l[i] = sectres["intr", i]
cd.l[i] = sectres["cd", i]
gd.l[i] = sectres["gd", i]
id.l[i] = sectres["id", i]
dst.l[i] = sectres["dst", i]
dk.l[i] = sectres["dk", i]
it[i] = Number(1).where[e.l[i] | m.l[i]]
inn[i] = not it[i]
k.fx[i] = k.l[i]
m.fx[inn] = 0
e.fx[inn] = 0
l.fx[i, lc].where[l.l[i, lc] == 0] = 0
p.lo[i] = 0.01
pd1.lo[i] = 0.01
pm.lo[it] = 0.01
pk.lo[i] = 0.01
px.lo[i] = 0.01
x.lo[i] = 0.01
xd.lo[i] = 0.01
m.lo[it] = 0.01
xxd.lo[it] = 0.01
wa.lo[lc] = 0.01
intr.lo[i] = 0.01
y.lo[...] = 0.01
e.lo[it] = 0.01
l.lo[i, lc].where[l.l[i, lc] != 0] = 0.01
# Equation Definitions
# price block
pmdef = Equation(cont, name="pmdef", domain=[i])
pedef = Equation(cont, name="pedef", domain=[i])
absorption = Equation(cont, name="absorption", domain=[i])
sales = Equation(cont, name="sales", domain=[i])
actp = Equation(cont, name="actp", domain=[i])
pkdef = Equation(cont, name="pkdef", domain=[i])
pindexdef = Equation(cont, name="pindexdef")
# output block
activity = Equation(cont, name="activity", domain=[i])
profitmax = Equation(cont, name="profitmax", domain=[i, lc])
lmequil = Equation(cont, name="lmequil", domain=[lc])
cet = Equation(cont, name="cet", domain=[i])
esupply = Equation(cont, name="esupply", domain=[i])
armington = Equation(cont, name="armington", domain=[i])
costmin = Equation(cont, name="costmin", domain=[i])
xxdsn = Equation(cont, name="xxdsn", domain=[i])
xsn = Equation(cont, name="xsn", domain=[i])
# demand block
inteq = Equation(cont, name="inteq", domain=[i])
cdeq = Equation(cont, name="cdeq", domain=[i])
dsteq = Equation(cont, name="dsteq", domain=[i])
gdp = Equation(cont, name="gdp")
labory = Equation(cont, name="labory")
capitaly = Equation(cont, name="capitaly")
hhtaxdef = Equation(cont, name="hhtaxdef")
gdeq = Equation(cont, name="gdeq", domain=[i])
greq = Equation(cont, name="greq")
tariffdef = Equation(cont, name="tariffdef")
premium = Equation(cont, name="premium")
indtaxdef = Equation(cont, name="indtaxdef")
netsubdef = Equation(cont, name="netsubdef")
# savings-investment block
hhsaveq = Equation(cont, name="hhsaveq")
gruse = Equation(cont, name="gruse")
depreq = Equation(cont, name="depreq")
totsav = Equation(cont, name="totsav")
prodinv = Equation(cont, name="prodinv", domain=[i])
ieq = Equation(cont, name="ieq", domain=[i])
# balance of payments
caeq = Equation(cont, name="caeq")
# market clearing
equil = Equation(cont, name="equil", domain=[i])
# objective function
obj = Equation(cont, name="obj")
# price block
pmdef[it] = pm[it] == pwm[it] * er * (1 + tm[it] + pr)
pedef[it] = pe[it] == pwe[it] * (1 + te[it]) * er
absorption[i] = (
p[i] * x[i] == pd1[i] * xxd[i] + (pm[i] * m[i]).where[it[i]]
)
sales[i] = px[i] * xd[i] == pd1[i] * xxd[i] + (pe[i] * e[i]).where[it[i]]
actp[i] = px[i] * (1 - itax[i]) == pva[i] + Sum(j, io[j, i] * p[j])
pkdef[i] = pk[i] == Sum(j, p[j] * imat[j, i])
pindexdef[...] = pindex == Sum(i, pwts[i] * p[i])
# output and factors of production block
activity[i] = xd[i] == ad[i] * Product(
lc.where[wdist[i, lc]], l[i, lc] ** alphl[i, lc]
) * k[i] ** (1 - Sum(lc, alphl[i, lc]))
profitmax[i, lc].where[wdist[i, lc]] = (
wa[lc] * wdist[i, lc] * l[i, lc] == xd[i] * pva[i] * alphl[i, lc]
)
lmequil[lc] = Sum(i, l[i, lc]) == ls[lc]
cet[it] = xd[it] == at[it] * (
gamma[it] * e[it] ** rhot[it] + (1 - gamma[it]) * xxd[it] ** rhot[it]
) ** (1 / rhot[it])
esupply[it] = e[it] / xxd[it] == (
pe[it] / pd1[it] * (1 - gamma[it]) / gamma[it]
) ** (1 / (rhot[it] - 1))
armington[it] = x[it] == ac[it] * (
delta[it] * m[it] ** (rhoc[it] * (-1))
+ (1 - delta[it]) * xxd[it] ** (rhoc[it] * (-1))
) ** (-1 / rhoc[it])
costmin[it] = m[it] / xxd[it] == (
pd1[it] / pm[it] * delta[it] / (1 - delta[it])
) ** (1 / (1 + rhoc[it]))
xxdsn[inn] = xxd[inn] == xd[inn]
xsn[inn] = x[inn] == xxd[inn]
# demand block
inteq[i] = intr[i] == Sum(j, io[i, j] * xd[j])
dsteq[i] = dst[i] == dstr[i] * xd[i]
cdeq[i] = p[i] * cd[i] == Sum(
hh, cles[i, hh] * (1 - mps[hh]) * yh[hh] * (1 - htax[hh])
)
gdp[...] = y == Sum(hh, yh[hh])
labory[...] = yh["lab_hh"] == Sum(lc, wa[lc] * ls[lc]) + remit * er
capitaly[...] = (
yh["cap_hh"]
== Sum(i, pva[i] * xd[i])
- deprecia
- Sum(lc, wa[lc] * ls[lc])
+ fbor * er
+ ypr
)
hhsaveq[...] = hhsav == Sum(hh, mps[hh] * yh[hh] * (1 - htax[hh]))
greq[...] = gr == tariff - netsub + indtax + tothhtax
gruse[...] = gr == Sum(i, p[i] * gd[i]) + govsav
gdeq[i] = gd[i] == gles[i] * gdtot
tariffdef[...] = tariff == Sum(it, tm[it] * m[it] * pwm[it]) * er
indtaxdef[...] = indtax == Sum(i, itax[i] * px[i] * xd[i])
netsubdef[...] = netsub == Sum(it, te[it] * e[it] * pwe[it]) * er
premium[...] = ypr == Sum(it, pwm[it] * m[it]) * er * pr
hhtaxdef[...] = tothhtax == Sum(hh, htax[hh] * yh[hh])
depreq[...] = deprecia == Sum(i, depr[i] * pk[i] * k[i])
totsav[...] = savings == hhsav + govsav + deprecia + fsav * er
prodinv[i] = pk[i] * dk[i] == kio[i] * invest - kio[i] * Sum(
j, dst[j] * p[j]
)
ieq[i] = id[i] == Sum(j, imat[i, j] * dk[j])
# balance of payments
caeq[...] = (
Sum(it, pwm[it] * m[it])
== Sum(it, pwe[it] * e[it]) + fsav + remit + fbor
)
# market clearing
equil[i] = x[i] == intr[i] + cd[i] + gd[i] + id[i] + dst[i]
# objective function
obj[...] = omega == Product(
i.where[cles[i, "lab_hh"]], cd[i] ** cles[i, "lab_hh"]
)
er.fx[...] = er.l
fsav.fx[...] = fsav.l
remit.fx[...] = remit.l
fbor.fx[...] = fbor.l
pindex.fx[...] = pindex.l
mps.fx[hh] = mps.l[hh]
gdtot.fx[...] = gdtot.l
ls.fx[lc] = ls.l[lc]
model1 = Model(
cont, name="model1", equations=cont.getEquations(), problem="cns"
)
model1.solve()
import math
assert math.isclose(
omega.records["level"].tolist()[0], 339.21, rel_tol=0.001
)
print(
"\nObjective Function Variable <omega>: ",
round(omega.records.level.tolist()[0], 2),
)
print("\nDomestic prices:\n", pd1.records.set_index("i").level)
if __name__ == "__main__":
main()
