Population Aging and Inventive Activity

in Macroeconomic Dynamics (2022), 26

This research empirically establishes and interprets the hypothesis that the relationship between population aging and inventive activity is hump-shaped. We estimate a reduced form, hump-shaped ... [more ▼]

This research empirically establishes and interprets the hypothesis that the relationship between population aging and inventive activity is hump-shaped. We estimate a reduced form, hump-shaped relationship in a panel of 33 OECD countries over the period 1960–2012, as well as in a panel of 248 NUTS 2 regions in Europe over the period 2001–2012. The increasing part of the hump may be associated with various channels including the acknowledgement that population aging requires inventive activity to guarantee current and future standards of living, or the observation that older educated workers are more innovative than their young peers. The decreasing part may reflect the tendency of aging societies to lose dynamism and the willingness to take risks. [less ▲]

A Note on the Characterization of the Neoclassical Production Function

in Macroeconomic Dynamics (2016)

We study production functions with capital and labor as arguments that exhibit positive, yet diminishing marginal products and constant returns to scale. We show that such functions satisfy the Inada ... [more ▼]

We study production functions with capital and labor as arguments that exhibit positive, yet diminishing marginal products and constant returns to scale. We show that such functions satisfy the Inada conditions if i) both inputs are essential and ii) an unbounded quantity of either input leads to unbounded output. This allows for an alternative characterization of the neoclassical production function that altogether dispenses with the Inada conditions. While this proposition generalizes to the case of n > 2 factors of production its converse does not hold: 2n Inada conditions do not imply that each factor is essential. [less ▲]

Bridging the gap between growth theory and the new economic geo-graphy : The spatial Ramsey model

in Macroeconomic Dynamics (2009), 13(1), 20-45

We study a Ramsey problem in in¯nite and continuous time and space. The problem is discounted both temporally and spatially. Capital flows to locations with higher marginal return. We show that the ... [more ▼]

We study a Ramsey problem in in¯nite and continuous time and space. The problem is discounted both temporally and spatially. Capital flows to locations with higher marginal return. We show that the problem amounts to optimal control of parabolic partial differential equations (PDEs). We rely on the existing related mathematical literature to derive the Pontryagin conditions. Using explicit representations of the solutions to the PDEs, we first show that the resulting dynamic system gives rise to an ill-posed problem in the sense of Hadamard (1923). We then turn to the spatial Ramsey problem with linear utility. The obtained properties are significantly different from those of the non-spatial linear Ramsey model due to the spatial dynamics induced by capital mobility. [less ▲]