Computing equilibria of GEI by relocalization on a Grassmann manifold

An algorithm is described to compute equilibria of the general economic model with incomplete asset markets, that is, of GEI. The algorithm is based on the existence of a route of zeros of a homotopy whose domain includes the price simplex and a Grassmann Manifold. This route is followed, in effect, by localizing and following diffeomorphic pieces in Euclidean space, and by relocalizing as is necessary.     

Walrasian Tatonnement Auctions on the Tokyo Grain Exchange

The Tokyo Grain Exchange (TGE)’s itayose mechanism providesthe opportunity to analyze functioning Walrasian tâtonnementauctions (WTA). In 15,677 auctions conducted over 1997–1998for corn and redbean futures contracts, price formation is unexpectedlysimilar to that observed in continuous double auctions. Provisionalprices and pledges are informative. In contrast to behaviorobserved in experiments, few pledges are deceptive, becausethe traders participate repeatedly and because the auctioneerhas flexibility when changing the provisional price and endingthe auction. Both the risk of the auction ending and the moreequitable dispersion of information increase depth and the speedat which information is embodied in price.     

Excess demand and price formation during a Walrasian auction

We conduct a detailed analysis of the relationship between excess demand and the convergence of price to equilibrium during a real-world Walrasian auction, paying special attention to the size and speed of the price adjustment. Using data from the Tokyo Grain Exchange (TGE), we first show that because auctions for the various futures contracts occur sequentially, information becomes more evenly dispersed across traders as an auction sequence progresses. Then we show that excess demand is positively correlated with both the eventual price change and the speed with which price adjusts. As information becomes more evenly dispersed, the strength of these relationships weakens. Finally, though excess demand explains a large proportion of the variability of the change in price, it explains only a small proportion of the variability of the speed of adjustment.     

Effect of market access on sharing practices within two Huaorani communities

One explanation for meat sharing within hunter-gatherer communities is that sharing reduces variance in consumption that results from unpredictable harvests. If this food-risk reduction is the primary reason for sharing, then a good alternative to sharing would be selling meat in a market and using the cash to buy storable foods. We analyze the effect of market access on sharing behavior in two Huaorani communities in the Ecuadorian Amazon in order to test the hypothesis that hunters share mainly to reduce food risk. If this hypothesis is correct we expect to find that hunters are selling meat that would have otherwise gone into sharing networks. The alternative hypothesis is that sharing has multiple benefits, in addition to risk reduction, making sharing and selling imperfect substitutes. We find evidence that households use the market to reduce food risk, but that the amount of meat a hunter sells has no relationship with sharing intensity. Rather, the likelihood of selling meat simply increases with hunting returns. The results suggest that selling meat has lower expected benefits than sharing and so hunters first satisfy their sharing requirements and then sell any excess meat.     

Comparing the Profitability of a Greenhouse to a Vertical Farm in Quebec

Rapidly growing demand for year‐round fresh food, regardless of the weather or climate, is driving demand for controlled environment agriculture systems. Sales from greenhouses (GHs) are growing at 8.8%, while sales from vertical farms (VFs) are growing at 30%. It is commonly believed in industry circles that a VF cannot economically compete with a GH, due to the high cost of powering artificial lighting. Nonetheless, researchers have yet to analyze the economics underlying a VF, let alone compare the profitability of a VF to that of a GH. This research gap is particularly relevant to Canada, as it is uniquely positioned to be a leader in the VF market. Below, we report the results of a detailed simulation of the profitability of growing lettuce in a VF and in a GH located near Quebec City. Surprisingly, we find that the costs to both equip and run the two facilities are very similar, while the gross profit is slightly higher for the VF.