Opener's rebid after player N°4 has overcalled

Opener's rebid after an overcall (player 4)
After his partner's response and an overcall from player n°4, the opener may pass with a a poor hand and no fit. His partner has the opportunity to rebid if he wishes to.
1) Supporting the responder's major suit

with 4 cards and a minimum opening hand: raise at the lowest level
with 4 cards and a second zone opening hand : jump raise

2) A suit shift shows :

either a minimum opening hand with a 5-5 two suiter
or a strong opening hand and a two suiter (might be 5-4)

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Exercise E1002 PASS With this minimum opening hand and after player n°4's overcall.

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Exercise E1010 A raise at level 3 is not forcing. It shows an unbalanced second zone hand.. otherwise the opening would have been 1 NT...

3) NT rebid : after the partner has responded

1 NT with a correct first zone opening hand and a stopper in the overcalled suit
2 NT with a third zone handand two stoppers in the overcalled suit

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Exercise E1001 No fit in the major suits, stoppers in the overcalled suit... check if you can go for a NT game.

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Exercise E1003 After a 1 ♥ overcall, 2 NT is very precise : no 4 ♠ cards, double stopper in ♥.. and a 3rd zone hand, of course.

4) The Opener's Double.
After a 1-level response from the partner, it is used when no bid is possible with a strong hand. In this situation, it does not guarantee a 3-card fit, unlike the opener's rebid after an intervention in the second position.