Patented "price quotation system" -- How do we know if we infringe the patent?

To infringe one or more claims of a patent, your method/system or apparatus must comprise every feature claimed in the one or more claims of the patent. Let's take a simple case - imagine you are the first one to invent a chair - so you claim at least one leg, because the chair could have a central pedestal-type leg, a seat connected to the leg, and a back connected to the seat - three features. A second person comes along and invents a padded-seat chair - he gets a patent because no one has thought of adding padding or cushioning to the chair seat in order to render it more comfortable, but since his chair also includes the three features of the first patent, he infringes that patent. Now, here's an interesting additional scenario - the first patent owner becomes aware of the second patented chair and the first patent holder wants to manufacture the padded chair because he realizes that most people will prefer the more comfortable chair, but he can't manufacture that chair without infringing the second patent. So, A, the first patent holder wants to make B's chair based upon the second patent but can't without infringing, and B can't make his own chair without infringing A's patent - so they cross-license each other saying that each can make the padded chair with no infringement.