4-4 point low approach three-space low pincer double approach

Double Approach  

Double Approach

 

The white 'a' reply is a double kakari. is one way out of a double kakari. is not at b because you're not supposed to attach to the weaker (pincered) stone^[1]. Attaching to the pincered stone makes the pincer a bit superfluous. could also be at , but this is one possible joseki. White get's the left side, and black get's the top side - which is what black was hoping for with the pincer at . - Fhayashi