The end is that yes, fiscal transfers are indeed the only way in which a single currency area can be kept together.
The big question is, how large do those fiscal transfers have to be in order for such a single currency area to work?
The September figures show exports to the single currency area have now started to fall - they were down 0.2% on the month.
Something very close to this is necessary, in the IMF's view, to manage this and future crises and build a stable single currency area.
But Thursday's data means that the 17 countries of the single currency area have not expanded as a group since the autumn of 2011.
It makes no sense to have a lot of exchanges in a single currency area, because they disperse liquidity and keep trading costs high.
The strong euro undermines the competitiveness of European exporters, and also drags down inflation in the single currency area due to the cheapening of imports.
Mario Draghi hinted last week that if leaders could credibly commit to tougher budget rules within the single currency area, "other things might follow".
Now, the sense among many investors is that the acute phase of the crisis is over and that the single currency area has turned a corner.
Still, the Treasury concluded in 1997 that it would do better within the single currency area than outside it, so it is likely to stick with that assessment.
Construction across the euro zone continued to decline in July, indicating the single currency area will likely struggle to post economic growth in the third quarter of this year.
Cyprus may be one of the eurozone's tiniest economies - its third smallest - but for the next 48 hours or so, it may be the single currency area's most important.
The country -- one of four eurozone countries to request a sovereign bailout -- is also grappling with unemployment of over 27%, the highest in the single currency area, according to Eurostat, the Commission's data service.
Although Cyprus is the smallest eurozone country to be bailed out, the details of the plan sent shockwaves through the single currency area as it was the first time European authorities have targeted people's bank accounts.
The prime minister said all Europe's economies, whether in the euro or not, needed a swift resolution of the current instability, and the single currency area as a whole needed to act to demonstrate it could "live within its means".
Under the terms of the deal, this supervisory body will oversee the eurozone's banks and use the single currency area's rescue funds, the European Financial Stability Facility or European Stability Mechanism, to aid banks directly without adding to governments' debt.
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French President Francois Hollande said the meeting of the 17 eurozone heads of state, held after the leaders of the EU countries outside the single currency area had left, was the result of pressure from Spain and Italy quickly to find short-term measures to stabilize the markets.
However, businessmen across the eurozone operating in the retail sector did not show greater confidence, according to the survey, chiming with separate survey data from research firm Markit that indicated retail sales across the single currency area fell for the fifteenth month in a row in January.
This would have an impact on the other 16 nations in the eurozone single-currency area, it warned.
First, it makes the job of the European Central Bank difficult, because the bank has to set interest rates for the whole single-currency area.
EMU, its interest rates would be set by the European Central Bank, which would be guided by the inflationary outlook in the whole single-currency area.
Within the single-currency area competitiveness has to be regained the hard way by pushing down domestic costs or increasing productivity rather than the easier-to-swallow medicine of devaluation.
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And Stern said reliability and a local clientele is part of the reason Patek Philippe has not fallen victim to the problems plaguing the single currency euro area.
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Both are attempting to implement structural reforms, while cutting taxes, and both are certain this year to breach the stability pact's 3% limit on budget deficits for countries within Europe's single-currency area.
Indeed, the most important potential benefit of this bigger break-up is that it could bring the euro crisis to a decisive end by restoring confidence in a smaller but sturdier single-currency area.
Since those economies together make up around one-third of euro-zone GDP, over the next few years the ECB will achieve its overall inflation target of 2% only if the healthier economies within the single-currency area (above all Germany) accept relatively higher inflation.
In order to preserve the euro, the single currency and thus also the single interest rate area that goes along with a single currency.
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The basic background is that for such a single currency to work it is necessary for there to be fiscal transfers across regions within the currency area.
The arrival of Europe's single currency will also increase price competition in the euro area.
In the euro area, the introduction of the single currency and the creation of an integrated financial market will change both the definition of the money supply and its relationship to inflation.
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