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Jan 6, 2023 at 14:57 history edited tsnao CC BY-SA 4.0
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Jan 3, 2023 at 0:20 history edited tsnao CC BY-SA 4.0
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Jan 3, 2023 at 0:04 comment added tsnao Okay, the difference between two examples is that $\mathcal{G}_t = \mathcal{B} [ 0, t ]$ is much bigger than the natural filtration of $X_t ( \omega ) = 1_{t = \omega}$, which is just $\mathcal{H}_t$, hence the analogy of the second example is not valid.
Jan 2, 2023 at 21:03 comment added tsnao @IosifPinelis, I'm clearly missing something... A singleton in the first example is a preimage of $X_t$, right? What is the difference then?
Jan 2, 2023 at 21:00 comment added Iosif Pinelis No, not of the same nature.
Jan 2, 2023 at 20:59 comment added tsnao @IosifPinelis, I mean, isn't the sigma-algebra generated by singletons in the first example of exactly the same nature?
Jan 2, 2023 at 20:56 comment added tsnao @IosifPinelis, shouldn't it only work if $X$ has some continuity (right-continuity or at least separability for instance)?
Jan 2, 2023 at 20:21 comment added Iosif Pinelis Concerning your modification, if $\mathcal{H}_t$ is generated by all finite subfamilies of $(X_s)_{s \in [0, t]}$, then $\mathcal{H}_t$ is the same as $\sigma$-algebra as the one generated by all $X_s$ with $s \in [0, t]$. Your first example seems fine to me.
Jan 2, 2023 at 19:28 history edited tsnao CC BY-SA 4.0
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Jan 2, 2023 at 19:15 history edited tsnao CC BY-SA 4.0
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Jan 2, 2023 at 18:57 history edited tsnao CC BY-SA 4.0
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Jan 2, 2023 at 18:51 history edited tsnao CC BY-SA 4.0
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Jan 2, 2023 at 18:40 history answered tsnao CC BY-SA 4.0