> Can you explain your thoughts? What have you tried/consider?
Thanks for the reply. What I understand is:
1. \(\displaystyle P(N_1=2, N_4=6)\) means "the probability of count of 2 items arriving at step-1, AND 6 items arriving at step-4.
2. \(\displaystyle P(N_1=2, N_4-N_1=4)\) means that "the probability of count of 2 items arriving at step-1 AND the 4 items as the difference of steps 4 and 1.
3. which is same as \(\displaystyle P(N_1=2, N_3=4)\) i.e. "the probability of count of 2 items at step-1 AND 4 items at step-3".
I understand (2) as (1) is represented as a "difference" term in (2).
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