Title: Sketch of a modeling framework
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6Sketch of a modeling framework F ? a LF ß
(e A) (1 ß ) (Food production)  s
LF / L (Definition
of s) Â M ? ? LM
(Urban-based manufactures) Â m M / L ? ?
( 1 s ) (Per capita manufactures) Â d? / dt
? m (Productivity
growth) Â n (1/L)dL/dt ? s
(Population growth) Note productivity growth
may allow for diffusion from abroad
7Assume per capita dietary needs are f and that
beyond dietary needs households have zero income
elasticity of demand for food. Assume also that
we begin in a region in which the basic dietary
needs can be met for the entire population. Â f
L ? a LF ß (e A) (1 ß )  Thus,  s f
(1/ ß) ? (a/ ß) s (1- ß)/ ß where s e
A / L (arable land in efficiency units,
per
capita)   (1/ s)(ds/dt) (a/ ß) ? ? (s - 1)
(1- ß)/ ß ? s   Depending on initial
conditions, s either approaches 0 (endogenous
growth) or 1 (Malthusian trap)
8The threshold degree of urbanization is t
a ?? / a ?? (1- ß)?  If s gt t
then the economy approaches Malthusian trap If
s lt t then the economy approaches
urban-based endogenous growth   Malthusian
trap is likely under the following
conditions  Low initial technology level ?
Low land per person (A/L) Low efficiency of
land (e.g. tropical ecozone) e Low urban
efficiency (e.g. landlockedness) ? Low degree
of learning by doing ?
9The Transition from Adoption (implementation)
to Innovation High concentration of innovators,
few cases of transition to innovation (exceptiona
l cases include Korea, Taiwan, Singapore,
Israel) Special public institutions play a key
role in the transition