Why is this move brilliant?

In this position, my opponent played b6, which is brilliant according to the engine. My previous move was Ng5, great move. So, I guess his knight on f7 was trapped whatever he did, but why on earth is b6 brilliant? Please ignore all the blunders I made according to game review.

The definiion of a brilliant move was changed two years ago,

Brilliant (!!) moves and Great Moves are always the best or nearly best move in the position, but are also special in some way. We replaced the old Brilliant algorithm with a simpler definition: a Brilliant move is when you find a good piece sacrifice. There are some other conditions, like you should not be in a bad position after a Brilliant move and you should not be completely winning even if you had not found the move. Also, we are more generous in defining a piece sacrifice for newer players, compared with those who are higher rated. 

Your move evidently meets those conditions.

/ https://support.chess.com/article/2965-how-are-moves-classified-what-is-a-blunder-or-brilliant-and-etc

I get stupid of best moves but I never get brilliant

At any rate, b6 was evidently considered to be a sacrificial move because your opponent would be losing his knight. (I didn't see that there was any choice in the matter. )

Before the move, your opponent was up by a piece and a couple of pawns.

After the move, your opponent had lost his material advantage but still had an even game.

That would fulfill the conditions from the computer part.

/ So the short answer is--- that the move was not "brilliant" in a way that a human would understand but met the programmed definition.

This practically is a textbook example of a "bug", right? It fits the programmed definition, but not at all what the programmer wanted.

idk

It's really hard to programmatically define what constitutes a human brilliancy and many players will disagree on what constitutes a brilliant move as well, which makes it even harder.

So, the site has decided on a definition where a move is brilliant if it allows the capture of material (sacrifices) and is good or best. There are some conditions around it, such as rating can influence it and if a position is completely winning, even without the sacrifice, it's not normally counted.

So, as long as a move meets the programmed criteria, it's not a bug.

That said, I believe there's some work around eliminating brilliants where it's not possible to save the material anyway and should be in a future update of the code

I understand your points of view, but in this case he had no choice, he did not sacrifice his piece on purpose. Still, I can see why it is brillant due to the algorithm explanation you guys gave.

The analysis thing wants to prove how smart and brilliant it is.

Wow. Great…explanation. I wonder how long it took you to type that. I’m not a long typer person. Anyway, I think the chess analyze thing had no brilliant moves to point out and just randomly made that move brilliant.

The review process doesn't do that

I agree with this one.

However, in my opinion there is pretty much zero chance of this to get into the code, unless the present behavior is reported as a bug. Otherwise, how would the programmers know what is going on?

Oh well

Similar situations have been mentioned to staff in the past and my understanding from those discussions are that is something being added. The Game Review code is constantly getting updates to make it better.

At any rate, b6 was evidently considered to be a sacrificial move because your opponent would be losing his knight. (I didn't see that there was any choice in the matter. )

Before the move, your opponent was up by a piece and a couple of pawns.

After the move, your opponent had lost his material advantage but still had an even game.

That would fulfill the conditions from the computer part.

/ So the short answer is--- that the move was not "brilliant" in a way that a human would understand but met the programmed definition.

for me how is ng5 a brillant move