Hello, I was reviewing U.S. history material and came upon the Yalta Conference. Could you simplify this conference into a mathematical or...

I'm not sure you realize how much you're asking for here---simplifying a pivotal historical event into a single mathematical formula would be a major achievement in political science, if it is even possible at all. (I was tempted to respond, "No, because I'm not Hari Seldon.") If I could really do what you're asking I should be publishing it in a journal, not here .

But I can at least give you something to work with here, an equation that will give you some sense of the significance of the Yalta Conference in historical affairs. Here's my equation:

Y = 20 e^{-0.05 (t - 1945)}

This equation represents at year t the number of war deaths Y, worldwide per 100,000 population. This is a first approximation; you could add some sine wave harmonics to make it better fit the surges of violence in the 1960s and 1980s. Even then, it's obviously an empirically-derived formula with no theoretical basis; there's no particular theoretical reason for war deaths to drop off exponentially, let alone sinusoidally.

But what we do know is that war deaths dropped off. Indeed, they dropped off extremely fast; as you'll see if you plug in today's date in that formula, the chance of any given person dying in war has fallen by a factor of more than 20 since the end of WW2.

This isn't just a result of the huge scale of WW2 either; you can extend the analysis further back to past wars, and while WW2 shows up as a spike (one of those higher sinusoidal harmonics, I suppose), overall there is a clear and approximately exponential trend of declining violence worldwide, and that trend accelerates rapidly after 1945.

Why? The leading theory is called the Pax Americana, a reference to the Pax Romana when the Roman Imperium held near-absolute military hegemony over most of Europe and the Middle East, and as a result wars were quite rare. Along a similar vein, and especially since 1990, the United States now holds near-absolute military hegemony over the entire world, and thus can prevent any major wars from starting. That hegemony was established at the end of WW2; personally I credit our aircraft carriers, overwhelming economic superiority, and nuclear weapons---but one thing that may have helped is the Yalta Conference, which established the US as a global superpower and restructured Western Europe to be democratic, and ultimately, prosperous.