Today I lost in winning position.

Now I had 1.5 points from 6. Ahead are only 3 rounds of our Swiss tourney. I don't take prize at all (I am not among the strongest in any way) but situation happened today is a shame.

Should I play the tourney till the end or make a phone-call to TD and say that I retire?

I was black. Black's move; black wins  but I lost...

Why quit the tourney... so you lost a game you maybe should have won... so what? Finish the tourament and see what else you can learn about chess while you are there. Don't pass up a learning opportunity! :-)

No, finish the tourney, you can still get 50%

I would suggest to take each game at the time and try to see if you can cause more trouble for your opponents in the remaining games.

In those kind of situations, I usually try to bring revenge on my next opponents for the blunders in the game i just lost.

I dont think you should quit out of tourney just because of bad luck so far, but in the end it is up to you.

But 1... b4?? was very stupid. I thought it was draw. I had 5 minutes on clock but I don't count((.

Yes< I still can get 50% (if I win last 3 games) but with equal opponents it's very hard to get 100% in 3 games.

have to ask, by the way... What did you do that lost this game above? As far as I can tell, you included no moves for us readers to go over.

My guess is he played b4...

Yes I did. Then white king catched my pawn and than captured on a6 and then REACHED b7 square.

In a swiss, with your score you will face weaker opposition. But that does not even matter. Fight for every half point. If you leave now yor score is 1.5/9. even if you get only one result it is already much better...

And if it's any consolation. I think the position is a draw, does anyone agree?

Withdrawing from a tournament is particularly unfair to those that you've already beaten or drawn against.  While their round results are marred by the loss of points in your games you are simply handing the players against who you've not finished your games the win.  In some cases this could be the difference between advancing and not making the cut.

Finish the round.

No, 1... Kh6 wins.

If your all about the prize, then quit

If your all about the rating, then keep playing and try to make up for losses

If your all about the chess, then keep playing you learn a lot from every loss

Black cant advance the b pawn before the K reaches b6.. after Kb6 b4, Kxa3, can Blck stop the a pawn?

I think it is great that you reached such an endgame!  You can learn so much from this.  Win or lose, as long as you now understand this endgame, you have a great advantage in the future.  Fight on!  We are here for the game, not for the results!!

Thanks for the answers. 7-th round is on tommorow evening. I think I should play.

There is no shame situation in chess! As others have already said here, you can always learn from your mistakes! 

I know how you fell, but you would make another mistake, a greater one if you retreat. Fight like a fighter till the end. And be ready for the next tournament. I am curious, what did you play in that position?

SO you've lost a match. THats that.I get it that u are probably disappointed but  I think i would continue. The experience is still good and i guess you could learn from it. It's up to you though...

Don't leave the tournament, try to take as much from it as you can!