What is the mathematical interpretation of random variable equation?

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Following is the equation: $$X = Y + Z.$$ $X, Y, Z$ are random variables. This is a random variable equation. What is the meaning of this equation? Does it mean that if you take any value of $Y$ and any value of $Z$, it should equal $X$? Or does it mean that when $Y$ and $Z$ are added, then $Y+Z$ will have same distribution as $X$?

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Random variables are defined as measurable functions from a probability space $\Omega$ into some target space. Without any further context, I interpret that equality as an equality of functions, e.g. $X(\omega) = Y(\omega) + Z(\omega)$ for every $\omega \in \Omega$. Quite often in probability, we only care about equality on a set of measure 1, and it is common to see $X = Y+Z$ a.s. where a.s. is an abbreviation for almost surely, which means that the functions $X$ and $Y+Z$ might differ on a tiny set of measure 0, but we don't care.