In a Grandmaster game between GM Emma and former Soviet Champion and world title candidate GM Leonid Stein, Stein puts his queen en prise after 20 minutes thought and Emma misses it !

what a bone head mistake. they must have been playing for a long time to make those mistakes. WOW!!!

I dont know what en prise means but is it that black could have mated with Qg2?

En prise basically means that a piece is not protected and can be captured. Anyways, no Qg2 would lead to Nxg2 and the loss of the queen. However, clearly I am suprised a GM would make such a mistake in either case...?

There are quite a few examples of this sort of thing - ''amaurosis scacchistica'' (a phrase coined by Tarrasch).  Like Reshevsky putting his queen en prise to a bishop and announcing mate, when he actually had a real mate if he played the right move.  I have some where GMs actually resigned when their next move would have won !  Want to see ? Say so and I'll post one later.

I would actually like to see that mxdplay4. If you wouldn't mind posting, that would be great. Thank you in advance.

Grandmasters can make mistakes?   It's a lie!

OK here's one.  Try and find the right move sequence as a puzzle if you like before looking at the solution.  This is a classic.  Popiel-Marco, 1902.  Marco to move resigned.  I made a mistake in the notes ; THE FINAL POSITION IS A WIN FOR BLACK NOT WHITE.  (But white actually won because black resigned)

interesting

Random.