Dealer S N/S Vul
(1) Inverted raise, showing a high card raise to thre diamonds or better.
This deal is from the final round of the Northern bridge league.
West leads the five of spades, playing fourth highest leads, you play the queen from dummy and East plays the four.
Obviously you will now make the contract even if the diamonds are three nil and you misguess, but you like to guess well, who should you play for the length in diamonds?
West appears to have lead from a four card suit, if he had a void diamond he would have a five card suit somewhere and would probably have lead that suit rather than a spade. So you should play West for the length in diamonds.