Inverted minors

The term inverted minors refers to a treatment used by the Kaplan-Sheinwold (K-S) bidding system for the popular card game bridge (Precision, as originally structured, also used inverted minors over a 1♦ opening). Under this treatment, a single raise of opener's minor suit is strong (usually at least 9 HCP up to 20 HCP), and a double raise is pre-emptive, showing a maximum of 8 HCP. Thus, the treatment inverts the usual structure of the single raise as weak and the double raise as showing limit raise strength.

The single or double raise promises at least five-card support for the minor. In the original version of K-S, and as further developed by Kaplan through the 1990s, both raises also deny a four-card major.

This treatment is well suited to a bidding system that employs the weak no trump. With 1NT used for balanced hands in the 12-14 HCP range, responder to a 1♣ or 1♦ opening knows that partner has either a good hand, 15-17 balanced, or an unbalanced hand with genuine length in minor suit. If opener has a three-card minor, he most often has a strong notrump hand; then, if desirable, it is easy to veer into no trump following the single raise.