# BBO Discussion Forums: Query about robot leads - BBO Discussion Forums

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## Query about robot leads

### #1thepossum

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Posted 2018-September-12, 17:51

Dear all

I'm curious about GIB defence to NT. Occasionally you can be brought unstuck by being the only hand where GIB selected different defence to all other tables. I have tried to identify how deterministic it's choice of leads can be. It obviously varies somewhat depending on intermediate bids in the auction. However in a case with identical bidding is it quite deterministic, or based upon statistical algorithms with uncertainty and some variation and on its choice. In this case you could be one of the unlucky outliers sometimes. I can't put it all down to GIB of course as a beginner but sometimes the lead makes all the difference as with a human. To be honest I don't think I would want entirely predictable and deterministic leads even from a robot. Then you would just be playing an optimisation machine. Just curious from a semi-professional point of view. I have started reading up on Bridge robots and AI and the complexity of Bridge because of the need to explain decisions, and not just make optimal decision without explanation

Regards P
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### #2johnu

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Posted 2018-September-12, 18:08

GIB will generate random hands fitting the bidding and run simulations based on the random hands. In theory, that's how opening leads and subsequent plays are determined.

Only a very limited number of simulations are done, and if a different random seed is used, a different sequence of random numbers are generated which will result in different random hands generated for analysis. Depending on the random hands, you can easily get different opening leads and subsequent plays.

If you are renting a robot and playing against others renting robots, I don't think a common random seed is used. And advanced robots and basic robots will sometimes make different bids and plays because of other programming which is independent of the random seed.
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### #3smerriman

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Posted 2018-September-12, 18:54

johnu, on 2018-September-12, 18:08, said:

If you are renting a robot and playing against others renting robots, I don't think a common random seed is used.

I'm pretty sure it is. But if you're using an advanced robot and comparing to a basic robot, of course everything will differ.
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### #4thepossum

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Posted 2018-September-14, 01:49

Thankyou. That's how I was expecting it worked. It just happened on a 3nt played by the N robot which made 2 or 3 overtricks depending on lead chosen by E robot
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