Editing David Ricardo (section)

====Contemporary theories====
{{Main|International trade theory#Ricardian trade theory extensions}}
Ricardo's idea was even expanded to the case of continuum of goods by Dornbusch, Fischer, and Samuelson<ref>{{citation |jstor=1828066 |pages=823–839 |last1=Dornbusch |first1=R. |last2=Fischer |first2=S. |last3=Samuelson |first3=P. A. |title=Comparative Advantage, Trade, and Payments in a Ricardian Model with a Continuum of Goods |volume=67 |issue=5 |journal=The American Economic Review |year=1977 |url=http://www.stanford.edu/~rstaiger/Comparativ-goods.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110516042952/http://www.stanford.edu/~rstaiger/Comparativ-goods.pdf |archive-date=16 May 2011 }}</ref> This formulation is employed for example by Matsuyama<ref>{{Citation |last1=Matsuyama |first1=K. |year=2000 |title=A Ricardian Model with a Continuum of Goods under Nonhomothetic Preferences: Demand Complementarities, Income Distribution, and North–South Trade |journal=Journal of Political Economy |volume=108 |issue=6 |pages=1093–1120 |url=http://darkwing.uoregon.edu/~bruceb/Peter%20W.pdf |archive-url=https://web.archive.org/web/20120918000912/http://darkwing.uoregon.edu/~bruceb/Peter%20W.pdf |archive-date=2012-09-18 |url-status=live |doi=10.1086/317684 |s2cid=154166748 |postscript=.}}</ref> and others.

Ricardian trade theory ordinarily assumes that the [[Wage labour|labour]] is the unique input. This is a deficiency as intermediate goods occupies now a great part of international trade. The situation changed after the appearance of [[:ja:塩沢由典|Yoshinori Shiozawa]]'s work of 2007.<ref>{{cite journal |last=Shiozawa |first=Y. |year=2007 |title=A New Construction of Ricardian Trade Theory: A Multi-country, Multi-commodity Case with Intermediate Goods and Choice of Production Techniques |journal=Evolutionary and Institutional Economics Review |volume=3 |issue=2 |pages=141–187 |doi=10.14441/eier.3.141|s2cid=154021080 }}</ref> He has succeeded to incorporate traded input goods in his model.<ref>Y. Shiozawa (2017) The new theory of international values: An overview. Shiozawa, Oka and Tabuchi (eds.) ''A New Construction of Ricardian Theory of International Values''. Singapore: Springer. Chapter 1, pp. 3–73.</ref> His theory became more useful by the discovery of new definition of regular international values (a couple of wage rates for countries and prices for products), because it is not defined as the normal vector at a facet of world production possibility set, which is the set where all countries enjoy full employment. The new definition is given in Shiozawa and Fujimoto (2018)<ref>Shiozawa, Y., and Fujimoto, T. (2018) The nature of international competition among firms. Fujimoto and Ikuine (eds.) ''Industrial Competitiveness and Design Evolution'', Springer Japan, Tokyo. Chapter 2, pp.43–96.</ref> and in Shiozawa (2020).<ref name="Shiozawa20"/> Shiozawa's theory of international values is now the unique theory of international trade that can treat unemployment and input trade in a general form.

Yeats found that 30% of world trade in manufacturing is intermediate inputs.<ref>{{cite book |last=Yeats |first=A. |chapter=Just How Big is Global Production Sharing? |editor-last=Arndt |editor-first=S. |editor2-first=H. |editor2-last=Kierzkowski |year=2001 |title=Fragmentation: New Production Patterns in the World Economy |publisher=Oxford University Press |location=Oxford |isbn=0-19-924331-X}}</ref> Bardhan and Jafee found that intermediate inputs occupy 37 to 38% in the imports to the US for the years from 1992 to 1997, whereas the percentage of intrafirm trade grew from 43% in 1992 to 52% in 1997.<ref>{{cite book |last1=Bardhan |first1=Ashok Deo |last2=Jaffee |first2=Dwight |year=2004 |chapter=On Intra-Firm Trade and Multinationals: Foreign Outsourcing and Offshoring in Manufacturing |editor-first=Monty |editor-last=Graham |editor2-first=Robert |editor2-last=Solow |title=The Role of Foreign Direct Investment and Multinational Corporations in Economic Development }}{{verify source|date=June 2019}}</ref>