!$ Y_t = 5 + e_t - 0,3e_{t - 1} !$ , em que !$ e_t !$ é um ruído branco, com distribuição normal, e satisfazendo as condições: !$ E(e_t) = 0 !$, !$ E(e_t^2) = σ^2 !$ e !$ E(e_t e_s) = 0 !$ para !$ t ≠ s !$.

São corretas as seguintes afirmativas sobre esse processo:

Item 4 - !$ Corr (Y_t, Y_{t-1})= −\dfrac{1}{4}. !$

!$ Y_t = 5 + e_t - 0,3e_{t - 1} !$ , em que !$ e_t !$ é um ruído branco, com distribuição normal, e satisfazendo as condições: !$ E(e_t) = 0 !$, !$ E(e_t^2) = σ^2 !$ e !$ E(e_t e_s) = 0 !$ para !$ t ≠ s !$.

São corretas as seguintes afirmativas sobre esse processo:

Item 3 - !$ Cov (Y_t, Y_{t-3})= 0. !$

!$ Y_t = 5 + e_t - 0,3e_{t - 1} !$ , em que !$ e_t !$ é um ruído branco, com distribuição normal, e satisfazendo as condições: !$ E(e_t) = 0 !$, !$ E(e_t^2) = σ^2 !$ e !$ E(e_t e_s) = 0 !$ para !$ t ≠ s !$.

São corretas as seguintes afirmativas sobre esse processo:

Item 2 - !$ Cov (Y_t, Y_{t-1})= σ^2 !$.

Russia and NATO

Outgunned

The Atlantic alliance faces superior conventional forces near Russia’s borders

The Economist print edition | Europe

March 10^th -16^th 2018 |

BOASTING about nuclear weapons is something Vladimir Putin clearly enjoys. In his annual stateof- the-nation speech on March 1st, he listed five new weapons. Russia’s president gave pride of place to the development of a nuclear-powered cruise missile with, in effect, unlimited range, which was guaranteed to thwart America’s missile defences (see Science). He got the headlines he wanted, though there is nothing new about Russia being able to devastate America with nuclear weapons, nor anything likely to change on that front. What should concern Europe more than Mr Putin’s nuclear sabre-rattling are the formidable conventional forces that Russia is steadily building up, particularly in the Baltic region.

On most measures, NATO appears comfortably ahead of Russia. Between them, America and its European NATO allies spent $871bn on defence in 2015, compared with Russia’s $52bn. But as a recent report by the RAND Corporation, a think-tank, argues, the reality on the ground is rather different. It finds that Russia would now enjoy significant local superiority in any confrontation with NATO close to its own border. NATO’s latent strengths, once they were brought to bear, would be too much for Russia to cope with. But in the early stages of a conflict, for at least the first month and possibly for a good deal longer, the alliance would find itself outnumbered, outranged and outgunned.

Since Russia’s invasion of eastern Ukraine in 2014, NATO has bolstered its forces in the Baltic region with what it calls its “enhanced forward presence”. By last summer, the alliance had a total of 4,530 troops near the border with Russia in four battle-groups led by Germany (in Lithuania), Britain (in Estonia), Canada (in Latvia) and the United States (in Poland). But, in accord with the 1997 NATO-Russia Founding Act, an anachronistic agreement that reflected a more optimistic time, the soldiers are not permanently based, but constantly rotate.

NATO has also beefed up its “very high readiness joint task-force” of about 5,000 more troops who can be deployed within a week. But it admits that neither force is more than a tripwire to convince Russia that any attack on them would be seen as an attack on the alliance as a whole.

Over the past decade, Western forces and their Russian counterparts have diverged in terms of capability. NATO members adjusted for counter-insurgency operations in places such as Afghanistan by restructuring with light expeditionary forces. Russia concentrated on rebuilding forces with the mobility and firepower to wage high-intensity warfare against a peer adversary. As part of a comprehensive effort at military reform following a disjointed performance in the war against Georgia in 2008, Russia has professionalised its forces (largely relegating conscripts to a second echelon), equipped them with modern heavy weapons, and honed them with frequent large-scale exercises and combat experience in Ukraine and Syria.