For the airfare-pricing bit, see &quot;Computational
Complexity Of Air Travel Planning&quot; [2003] by Carl
de Marcken of ITA Software:<p><a href="https:&#x2F;&#x2F;static.googleusercontent.com&#x2F;media&#x2F;www.itasoftware.com&#x2F;en&#x2F;&#x2F;pdf&#x2F;ComplexityofArlineTravelPlanning_Carl_Sep-03.pdf" rel="nofollow">https:&#x2F;&#x2F;static.googleusercontent.com&#x2F;media&#x2F;www.itasoftware.c...</a>