Usage of ...から参加し


> この会議には第2回から参加し、「今回のテーマは"システムズ×ひろげる"。

I'm having problems understanding the meaning of から参加し in the above sentence.
Is it something like "having participated since the 2nd conference"?




This 「から」 is a `Case particle` meaning " **from** or **since** ," which is
used when you want to tell a spacial or time/sequential _starting point._

  * 東京{とうきょう} _から_ -> **FROM** Tokyo (Spatial)
  * 7時{じ} _から_ -> **FROM/SINCE** 7 (Time)
  * 3番目{ばんめ} _から_ -> **FROM/SINCE** 3rd (Sequential, This case)

So, as you guessed, 「から参加し」 in this context is interpreted as "... participate
from ..." or "... participate since ..."  
In this specific case, we don't know when this "participation streak" ends, so
we get to choose `since`.

