# Which model of trade is this?

In a recent article, Paul Krugman showed these equations:

Which model is this? What do the symbols denote? Is the first symbol a v or nu?

• Given the curl on the right, I see a $\nu$ (nu) not a $v$ (vee) – Henry Nov 5 '16 at 10:10
• This question would be greatly improved by a link to Krugman's article. – Giskard Nov 5 '16 at 10:25
• @denesp As per your suggestion I've added a link, although it's an NYT piece so it may count towards peoples' articles per month limit. – J.G. Nov 5 '16 at 15:13