DEVELOPPEMENTS OF 1NT OPENINGS OVER OPPONENTS INTERFERENCE

1NT - (DBL) BY OPPONENTS(PENALTY)

    PASS♠WEAK OR BALANCED
♠        WANTS BY OPENER TO BID 5 CARD SUITS OR
♠        RDBL IF RHO PASS(S.O.S)
    RDBL♠9+HCP
    2♣   NATURAL
    2♦   NATURAL
    2♥   NATURAL
    2♠   NATURAL
    2NT♠ 2 SUITED
    3X♠  PREEMPT

1NT - (DBL) BY OPPONENTS (DONT)

    SYSTEM ON.RDBL 9+HCP

1NT - (2♣) BY OPPONENTS (CAPPELETTI)

    PASS  WEAK OR WANTS TO KNOW SUIT
    DBL  STAYMAN 
    SYSTEM ON

1NT - (2♣) BY OPPONENTS (LANDY MAJORS)

    PASS♠WEAK
    DBL♠ AT LEAST INV.
    2♦   5+♦ TO PLAY
    2♥   AT LEAST INV. ♠ SING.
    2♠   AT LEAST INV. ♥ SING.
    2NT♠ TRANSFER TO 6+♣
    3♣   TRANSFER TO 6+♦
    3♦   FG W 5 CARD MAJORS 3♥ ASK 3♠ = 5♠ 3NT = 5♥
    3♥   5+♣ 5+♦ ♥ SING. FG
    3♠   5+♣ 5+♦ ♠ SING. FG
    3NT♠ TO PLAY

1NT - (2♦) BY OPPONENTS(CAPP. MAJORS)

    PASS♠WEAK 
    DBL♠ AT LEAST INV.
    2♥   AT LEAST INV. ♠ SING.
    2♠   AT LEAST INV. ♥ SING.
    2NT♠ TRANSFER TO 6+♣
    3♣   TRANSFER TO 6+♦
    3♦   FG W 5 CARD MAJORS 3♥ ASK 3♠ = 5♠ 3NT = 5♥
    3♥   5+♣ 5+♦ ♥ SING. FG
    3♠   5+♣ 5+♦ ♠ SING. FG
    3NT♠ TO PLAY

1NT - NATUREAL OVERCALLS BY OPPONENTS(ONE OR 2 SUITED)

    PASS♠WEAK OR PENALTY
♠        (NO PASS WITH FG)
♠        (DBL BY OPENER IS OBLIGED WITH 2 CARDS)
    DBL♠ NEGATIF AT LEAST INV.
♠        (IF INV. WITH 2+ CARDS)
♠        (IF FG WITH 1+ CARDS)
    2X♠  TO PLAY

    BETWEEN 2NT AND 3♠ BIDS ARE TRANSFER 6+CARDS COMPETITIVE OR 5+CARDS FG
    TRANSFER TO CUE-BID GENERALLY SHORTNESS.

    3♠   5+♠ FG 
    3NT♠ TO PLAY


COMPETITIVE EXAMPLES


1)      1NT  PASS  PASS  DBL
        PASS 2X    DBL=PENALTY  (PARTNER OF DOUBLED SHOWS WEAKNESS)

2)      1NT  PASS  PASS  2♣(MAJORS)
        PASS 2M    DBL=PENALTY  (PARTNER OF DOUBLED SHOWS WEAKNESS)

3)      1NT  PASS  PASS  2X (NATURAL)
        PASS PASS  DBL=NEGATIF

4)      1NT  2♦(TRANSFER)  ?    DBL AFTER PASS IS PENALTY
♦                               DBL=NEGATIF
♦                               2♥=WANTS TO COMPETE
♦                               RUBENSOHL DEVELOPPEMENTS

5)      1NT  2♣ (ONE SUITED)  ? SYS ON

6)      1♦  1NT  DBL  ?

        ALL BIDS ARE NATURAL RDBL SOS
        2♣♦     5+♣ NATURAL
        2♦♦     5+♦ NATURAL
        2♥/♠    5+♥/♠ NATURAL
        PASS♦♦   FLAT HAND 4333 OR 4432