skip validation in parent class

I have a few classes deriving from A.A does some validationIn the specific case of class B that inherits from A, I'd like to skip the validation.

I'm using active interaction btw

class A < ActiveInteraction::Base  string :s  validate :valid  private  def valid    #raise something unless s equals "banana"  endendclass B < A   #do something here to skip A's validation??            def execute    #super cool logic  endend