I have noticed some SDK players on KGS will at times when the game is over and done with suddenly invade a defined territory just to cause chaos and praying that the player will misread and misplay.

I find such plays very rude. The player has soundly beaten you and you just jump into a fight to cause trouble. Also after their fool hearty invasion has been thwarted they abruptly resign and leave the game. I find such behavior not in accordance with the "fighting spirit" that is sometimes discussed but rather just a nuisance that is derived from their inability to accept defeat.

This doesn't occur every game but often enough to be pointed out. Does such behavior occur in low/high dan games? I of course never have seen a professional use such antics.

How does everyone else feel about such behavior?

Think of it as a learning opportunity, a gift, like all the other moves your opponents give you.
If you are correct that the invasion is hopeless, then just kill it. (And you can choose never to play this opponent again.)
If you cannot kill it, then study your mistakes.

Yes, it's not uncommon on Tygem.

It's fine.

Just kill it. Little else to it. Some people don't take losing well, that is unavoidable.

But you have to remember that to many people Go isn't so much about the culture and history and all that - it is an interesting game to compete in. Sometimes you just need to disrespect the opponent. You don't assume he knows how to hold something, you make him prove it. If an invasion is truly unreasonable, it should not be terribly difficult to find how to kill or block it. Similar thing to attitude towards hamete or the Tengen+Hilariously Unreasonable Greed guy from Battousai's lecture: Don't be indignant. It is just a game with stones on the board. Keep your cool and kill it. That is the object of the game and that is all there is to it on the board.

Not to confuse the latter with the former, though - it is perfectly possible to just play rude, vulgar and cutthroat on the board and be a nice person otherwise, this I often find is just a matter of self-esteem. If you're okay with yourself, you just play. You need to prop up a failing ego, you devolve into senseless rage more often than not or play something like League of Legends that's made to divert the blame for the loss to anything but yourself.

Depending on how terribly obvious (or unobvious) it is that that the group cannot be invaded in any meaningful way, sometimes people just aren't strong enough to know with 100% certainty that a group is fully secure.

When I think the game is over and an opponent makes an unreasonable invasion, I always ask myself "would it still be unreasonable if I passed?". If I think it would be then I always pass, even if the game rests on it. I find that this helps keep the game interesting, stops me losing because I was bored and not paying attention, and is good practice for those times when you want to tenuki an opponent's threat but aren't sure if you can. Of course, sometimes I lose because of it, but... meh.

P.s. As to whether it's okay to make these invasions, I think it depends on what your opponent is thinking. If it's just "I think I might be able to live there", then it's fine. If it's more like "my opponent is down to their last byo-yomi so I'll keep playing and hope they make a mistake", then it's not, but you can't know either way so just treat it like any other bad move and try to enjoy the game.

P.p.s. I now realise that a lot of what I used to think were unreasonable invasions were actually good ones. What was unreasonable was me thinking I could wall off large chunks of territory with thin walls full of ataris and cuts. I expect that as I get stronger I'll learn the same thing about some of the invasions I currently think are unreasonable.

I've seen this in real life and the defending player didn't even pay attention while he killed the invasion.

When I asked "how were you able to kill that invasion while chatting and watching my game?"

The answer was "I had already read out that invasion during the game. It's the only way to know if you need another stone to defend your area."

So, next time, during those times while your opponent thinks, read the possible invasions. It's much less annoying if you just drop the stones like following a tsumego you know.

I my experience, it also makes your opponent resign sooner when he understands you're just following the path to kill. If you think one minute per move, he gets his hopes up and keeps going on.

Also, sometimes you've read is so clearly that you see a chance to tenuki one of the invading moves. When I've done that, the resign came instantly.

Thank you for everyone's replies.

Just to clarify the instance I am speaking of is when both players have settled all of their territories and are both ready to pass then a player just decides to try his luck by throwing a stone into a group that might die if the player doesn't connect or continues to pass etc.

I like EdLee's point of view, I think that is the ideal answer.

I concur. You'll never get away from people who will try this and the only real way to deal with it is... to deal with it.

It's similar to a handicap situation I have with a player at my club. I'm currently taking 9 stones from him when we both know it should be much less. But though we both can say that, if either of it says "Prove it!" I'm back to 8-9 to win 50% of the time.

So work with last-minute unreasonable looking invasions the same way you should with any other play you look at and say, "That can't work!". Kill it or see where you went wrong.

But remember, have fun! Over the years, I've played many sequences I though were clever and good just to see them fail. I have to pass along my thanks to all the stronger opponents who should have been shaking their heads at me for not calling me out on them but instead showed me my errors on the board, with the stones.

Bruce "Pay it sideways" Young

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Currently reading: Plutarch, Cerebus, and D&Q 25th Anniversary

If you need 8-9 stones to win 50% of the time, why do you think that's not the right handicap? (This isn't a rhetorical question implying you're wrong; I'm generally curious.)

I actively appreciate that behavior since I like playing people who try to win. It's a total mystery to me what you find rude about it.

General consensus between both of us based on overall knowledge and skill and relative ratings on AGA scale. He's got my number and knows how to hit me harder than an "average" person of his rank since we've been playing for years. Basically I set myself up for all-or-nothing fights and lose them more often than not. So it's really my fault for not playing better against him.

Makes for fun games though! No competing moyos here!

Bruce "All or nothing or less than nothing" Young

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Currently reading: Plutarch, Cerebus, and D&Q 25th Anniversary

Seems both of you have a misunderstanding. The distance between any two persons is unique to the two persons.
It can be estimated but cannot be accurately derived from merely some artificial ratings.
(That is, it has nothing to do with any other third person(s), which is how the artificial ratings were calculated.)
It can only be accurately obtained by a sufficient amount of actual games between the two persons.
If 8-9 stones mean you get 50/50 when you play with this person, THAT IS the correct distance between you two.
It should NOT be much less; it should be exactly 8-9 stones.

(For example, this happens all the time: A can always beat B; B can always beat C; C can always beat A.)

@BaghwanB: That makes sense, and it sounds like it's highlighting some of your problems for you. You've made me wonder if I'm missing out by not having regular opponents...

How interesting Bruce,

We play each other even and I would probably say that I win more often than I lose. When I play this same unnamed player he has been giving me 4 stones, but after our last game we decided to move it down to 3. I think it is interesting how two players of similar skill against each other can fare so differently against a similar opponent. Then again, my level of play seems to change vastly based on circumstances. I have been 8-9k on dragon go since I started playing there. In the same time frame my KGS rank has gone up from 8k to 5k, my tygem rank has stayed steady at 9k, and on Kaya (where people keep on saying they have the same rank as on KGS) I am a steady 7k.

It's obviously proof that all rating systems are flawed and should be banned.

Bruce "The rule that proves the exception" Young

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Currently reading: Plutarch, Cerebus, and D&Q 25th Anniversary

One can imagine a triple of ko professionals A,B and C such that A beats B, B beats C and C beats A. Consistently.

This.

If you pass and the opponent still cannot accomplish anything, you have just gained one point. If he plays many unreasonable moves, keep passing until you have to respond. Now for the surprising mathematical formula. Amount of points gained = n, where n is the number of passes you can make.

Why is this an important choice to make? Not becaus the point per pass, but because it trains our reading ability in relation to cuts and shortages of liberties (if unreasonable cuts) and life and death (if invasion on the side).

A quibble:
Technically, this depends on the ruleset. If you play using Chinese rules (area scoring) or a ruleset that fakes territory scoring by using pass stones (like AGA rules), you don't actually gain any points by passing. Playing dame, on the other hand...