一般均衡理論
General equilibrium theory

context: zh_tw: 如果一種產業很少使用某種生產要素，該產業產出的增加不會使該要素價格上升。如果進行一階近似，該產業中的廠商不會面臨成本遞減，該產業的供給曲線也不會向上傾斜。如果一種產業大量使用某種生產要素，該產業產出的增加將導致成本下降。但此種要素很可能被用於生產該產業產品的替代品，因此該要素價格的上升將對這些替代品的供給產生影響。斯拉法因此認為這下假設之下原產業需求曲線的一階效應包括了該產業產品替代品的供給曲線的移動，繼之以原產業供給曲線的移動。一般均衡旨在研究市場間的此類互動。
en: If an industry uses little of a factor of production, a small increase in the output of that industry will not bid the price of that factor up. To a first-order approximation, firms in the industry will experience constant costs, and the industry supply curves will not slope up. If an industry uses an appreciable amount of that factor of production, an increase in the output of that industry will exhibit increasing costs. But such a factor is likely to be used in substitutes for the industry's product, and an increased price of that factor will have effects on the supply of those substitutes. Consequently, Sraffa argued, the first-order effects of a shift in the demand curve of the original industry under these assumptions includes a shift in the supply curve of substitutes for that industry's product, and consequent shifts in the original industry's supply curve. General equilibrium is designed to investigate such interactions between markets.
qas: question: zh_tw: 斯拉法認為原產業中哪些方面的重要移動應該屬於一階效應？
en: A consequential shift in what aspect of the original industry did Sraffa believe should be expected to be first-order effects?
answers: zh_tw: text: 需求曲線
en: text: the demand curve

context: zh_tw: 對該理論要素的三條重要解說常被引述。首先，假設商品由其所配送的地點加以區分。這樣 Arrow-Debreu 模型就是一個空間模型（例如國際貿易）。其次，假設商品由其所配送的時間加以區分，即假設所有市場在期初即刻達到均衡。該模型中參與者購買並出售合約，而這些合約規定要配送的商品及其傳送時間。跨期均衡的 Arrow–Debreu 模型包括所有商品在所有時間點的遠期市場。不存在未來時間點的市場。第三，假設合約指定影響一商品是否被配送的性質狀態：“除去其物理狀態、位置與日期，一個商品轉讓的合約指定了確定其發生條件的事件。這一新的商品定義允許從任意機率概念出發得出無 [風險] 的理論。” 這些解說可以整合。完整的 Arrow–Debreu 模型可以說適用於商品由其所配送的地點、時間與情境及其固有本質區分的情形。因此存在一個完全的合約價格集，例如 “1 噸紅冬小麥，1 月 3 日自明尼阿波利斯發貨，如果 12 月佛羅里達有颶風”。由此類完全市場構成的一般均衡模型似乎與描述現實經濟執行機制相去甚遠，然而其支持者強調這仍不失為現實經濟運作的簡化表述。
en: Third, suppose contracts specify states of nature which affect whether a commodity is to be delivered: "A contract for the transfer of a commodity now specifies, in addition to its physical properties, its location and its date, an event on the occurrence of which the transfer is conditional. This new definition of a commodity allows one to obtain a theory of [risk] free from any probability concept..."These interpretations can be combined. So the complete Arrow–Debreu model can be said to apply when goods are identified by when they are to be delivered, where they are to be delivered and under what circumstances they are to be delivered, as well as their intrinsic nature. So there would be a complete set of prices for contracts such as "1 ton of Winter red wheat, delivered on 3rd of January in Minneapolis, if there is a hurricane in Florida during December". A general equilibrium model with complete markets of this sort seems to be a long way from describing the workings of real economies, however its proponents argue that it is still useful as a simplified guide as to how real economies function.
qas: question: zh_tw: 基於這個模型，佛羅里達州在冬季颶風期間需要什麼產品？
en: What product based on the example does Florida need during winter hurricane?
answers: zh_tw: text: 紅冬小麥
en: text: red wheat