PITBULLS:

Competing with D.S.I.P. doubles means undoing all your instinctive doubling habits from your Bridge puppyhood. Trump stack doubles simply do not exist in competitive auctions as the initial action. The concept of doubling initially to extract penalty bonuses are extinct. D.S.I.P. doubles only apply where there is an element of competition . Competing is defined as bidding when nobody owns the auction or you can not tell from the bidding.

Trump stack penalty doubles should only be made when the partnership has already announced their hands so no need for guess work or "pulling" trump stack doubles. The rule for leaving in penalty doubles is do I have what can be reasonably expected from the bidding ? In D.S.I.P. theory , you describe your hand first and all subsequent penalty doubles are left in.

D.S.I.P. doubles are a pre-requisite for trump stack penalty doubles. You announce your defense via quick tricks along with your desire to compete again by doubling . Partner knows that you have no duplication of value in their suit and can act accordingly. Once hands have already been announced , penalty doubles ( trump stack) may commence later in the auction.

D.S.I.P. doubles borrow heavily from negative doubles in that penalty doubles result from conversions. A D.S.I.P. double asks permission from partner to compete again. Partner has her say in this decision and can nix the request if holding their suit. These doubles apply as the initial action thru 4♠ . Trump stack doubles kick in at the 5 level.

To use D.S.I.P. doubles effectively , you must know when they do not apply. They do not apply when your partnership has pre-empted as your hand has already been announced. D.S.I.P. doubles do not apply when you own the auction as forcing pass theory takes over.

Conventional doubles like negative doubles , T/O doubles, re-opening doubles , responsive doubles , game try doubles & support doubles are all a subset of D.S.I.P. doubles. You want to compete but do not necessarily own the auction. Conceptually all doubles in Bridge apply in only two instances - when you own the auction and when you do not.

When you overcall and follow up with a double , it is not penalty nor takeout. It is D.S.I.P. saying I want to bid again but I have defense in case you want to defend. A T/O double and a subsequent double is not penalty. It just means that I want to bid again with a big hand but will be happy to defend if that is your decision. For auctions that the double is confusing the default understanding is D.S.I.P. rather than forcing pass theory understandings.