Efos/Extended Stayman

Lars Marjoniemi submitted this useful convention to me via e-mail on 4/18/98. Efos allows a partnership to find 4-4 and 5-3 major fits, as well as minor suit fits.

Efos may be used to search for major and minor suit fits after a strong notrump opening. Responder bids 2C to ask about opener's hand, and opener responds as follows:

2D=no 4card major and mnimum opening (15-16 HCP)
2H=4card major 15-18 HCP
2S=4card major 15-18 HCP
2NT=both major and minimum (15-16 HCP)
3C= no four card major and maximum (17-18 HCP)
3D= 2-2 in the majors and maximum (17-18 HCP)
3H= 5 cards in hearts and 17-18 and 2card in other major
3S=5card and 17-18 and 2card in other major
3NT=4-4 in major and 17-18

After a 2D response, Responder may bid 3C to ask for a 3 card major. Opener bids

3D = No three card major suit (note -- this is the exactly the same as the 3D response above -- must have 2/2 in the majors)
3H/3S = three card support in that major suit
3NT = three cards in both majors

Response may also ask for Opener's best minor with by bidding 4C after receiving a 3D response (opener must haveat least 5-4 in the minors)

Partner may

Pass = 5+ cards in clubs and a minimum
Bid 4D = 5+ cards in diamonds and a minimum
5C = 5+ cards in clubs and a maximum
5D = 5+ cards in diamonds and a maximum