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Psandman, thnx for your time. I appreciate it very much.

at #1: i think u misread it.
Did u notice that 4 ppl in total are in the pot. after the allin there are still 3 ppl with a stack in that pot. It cant be a showdown there, doesnt the action just continue?
IMO he can raise to isolate or for value. The question is what is the amount he can reraise?



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Although its been reiterated that the answer was correct maybe I can explain a little bit more. When you make a bet or call when the action gets back around to you can only raise if the action has been re-opened to you. In NL the action is only re-opened if there has been a full sized raise. And that is measured from what a full sized raise is at the time the player in question made his previous action.

In your example one, player B was the first to bet and he set the minimum bet size for that round, $500 dollars. A simple way to know whether he can raise is to know what the bet size is when it gets back to him. Since the minimum bet/raise is now $500, the action is open to him if somebody raises to $1000. In this case when it gets back to him, the bet is at $900, the action isn't open to him, he can only call or fold.

Now instead imagine player A bet $200, player B raised to $500, player C called, and player D made it $900 all-in and player A calls. Well, the minimum raise when Player B made it $500, became $300 (he raised $300 over the initial $200 bet from A) So to open the action to B, it would have to come back to him as an $800 dollar bet. In this case it came back to him as $900 so the action is open and he can fold, call, or raise.

Hopefully that's clear.

Robert's Rules covers all this by the way although the wording is not very easy on the eyes:

No Limit:

3. All raises must be equal to or greater than the size of the previous bet or raise on that betting round, except for an all-in wager. Example: Player A bets 100 and player B raises to 200. Player C wishing to raise must raise at least 100 more, making the total bet at least 300. A player who has already acted and is not facing a full-size wager may not subsequently raise an all-in bet that is less than the minimum bet or less than the full size of the last bet or raise. (The half-the-size rule for reopening the betting is for limit poker only.)

Edit: Sorry Rule 4 of the NL section of Robert's Rules, even more directly answers your question:

4. Multiple all-in wagers, each of an amount too small to qualify as a raise, still act as a raise and reopen the betting if the resulting wager size to a player qualifies as a raise. Example: Player A bets $100 and Player B raises $100 more, making the total bet $200. If Player C goes all in for less than $300 total (not a full $100 raise), and Player A calls, then Player B has no option to raise again, because he wasn’t fully raised. (Player A could have raised, because Player B raised.)