Alan Fortuny Sicart

Solow stated in 2008 that there is no reason for capitalism to exist in a steady state, and this is the main conclusion after we analyse the neoclassical literature. There are multiple conditions where economies could function without growth, and such economies almost always have better environmental state than those that grow. Those theories also called supply side economics, state unanomously that the condition for stable output and emissions is a constant supply of effective (actual input * productivity) input remains constant.  That could be done by either reducing the input in line to the technological progress on that input or redirecting input usage and technology to the clean ones (labor instead of resources, and renewable sectors instead of fossil fuel based).  To achieve that, regulation is needed. A cap on input use have to be in place for example for resource use or taxes on the dirty sectors will deviate production to cleaner sectors that are more intensive in lab...

  Dasgupta-Heal-Solow-Stigliz Model (1974) The following model adds limited natural resources to a model similar to the one developed by Sollow. The stock of the non-renewable resource is depleted at the following rate and overall lower than the initial stock: These model assume constant susbtitution elasticities between the factors K,L, R. As Resource availability is strictly decaying, economic growth require significant amounts of factor substitution . So significant as natural resources need to become inesential in the production process.  Another alternative of the model is resource augmenting technology, where that leads to an increase in effective natural resource avaialability bigger than the decline of the resource stock . The third option to explain long term economic growth is by permanently increasing the other factors, capital and labor. That would be easier the higher the productivity of those factors is. Green Solow Model with abatement The green Solow model kee...

  AK Model of Humand Capital In this model, there are no decreasing marginal returns on capital as in the models presented in part 2.1.If capital K is consider to reflect the accumulated knowledge and physical capital, this can be consider to provide constant and not reducing returns to scale. That lead to the following equations for the determinats of the growth of output: That ultimately means that a s long as the technological progress growth is higher than the disccounted dereciation of capital, output will grow at a pace equally to the growth of that general concept of capital (human and physical). Zero growth conditions In this model, increases in the productivity t have to be compensated by reductions in the accumulation of capital at the same rate . That would happen if depreciation or saving preferences change in the direction to lower savings and higher depreciation. While here the determinants of growth are engogenous determined, the casual separation between technolog...

 Foundations In this theories, two agent types determines the level of production, consumption, investment, labor demand...which are homogeneous firms and homogeneous workers. Firms maximize profits producing more till the point where marginal revenue equals marginal costs. Households are workers decide how much to work given the interest rates and wages, together with their preferences. Their income comes from labor, savings and firm's profits (they are both workers and owners). Due to the decreasing marginal productivity of the input factors and also consumption in the utility function, more work and consumption ultimately contributes less and less to the utility. Labor supply is positively related to the level of wages (the opposite happens with labor demand). Consumption decisions over time depend on the interest rates, as higher interest rates makes more appealing saving. In this context there is no unemployment, as all labor is used and adjusted to the productivity levels on ...

 Motivation Economic Growth is a relative recent thing, as it barely exists before the XIX century.  The division of labor and use of dense/cheap but polluting forms of energy explain our increases in productivity, but also a destruction of the environment and the exhaustion of the commons that is imprecendented in human history at least. Pursuing a steady state economy, and the study of the the macroeconomics of the steady state is not about going back in time, but rather comply with resources and environmental limits, achieve sufficiency, in a economic system that avoids the growth mandate while improve wellbeing intra/inter generations. In my first paper [1], I showed the limitations of growth in multiple dimensions and the impossibility to achieve aggregate growth without facing social, resource, energy and environmental crises. While the case that we need to stop growing has been made, what remains to  be investigated is the macroeconomic conditions of economies wi...

 Momentum Contrast for Unsupervised Visual Representation Learning(MOCOv2) In the previous post, we present SIMCLR as one of the most promising self-supervised image representation methods. As the caviat of long training and large batch sizes could be too much for many applications, Mocov2 and its subsequent versions are both exploration. https://arxiv.org/pdf/1911.05722.pdf Introduction Self supervised methods in NLP are the norm, and almost how they have been built. Language tasks haven been made more and more efficient with the usage of dictionaries and keys on attention models, where memory is manage very efficiently on very large texts.  The obvious continouous, highly dimensional nature of image data should not be a block for leveraging the learnings from NLP in self supervised tasks and representations in computer vision. Moco is a great proof of how it can be done. If we reframe keys and tokens in the forms of group of images that are similar in the same query and disi...

 SIMCLR: simple framework for contrastive learning representations As from the previous post, this is aimed to summarize the following paper, in the next post we cover moco and its benefits from a computational standpoint. Let's get started: https://arxiv.org/pdf/2002.05709.pdf Introduction Viual representations can be done with generative (VAE or GANS) or discriminative methods (like SIMCLR or MOCO) when labels are not available. Generative methods are expensive to compute, and have some issues as shared in the part 1 of this post. In this paper we see how a discriminative approach, which replicates a supervised tasks on self generated labels is performing state of the art results. Not only that, but SIMCLR is also more intuitive, requiring a much simple architecture. The major components of that framework are: contrastive tasks based on data augmentations the contrastive loss contains a non-linear component to improve the quality of the representation large batch sizes and long t...