{ "items" : [
    { "id" : "http://dbpedia.org/resource/Calculus_of_variations"
      "properties" : {
        "http://www.w3.org/2000/01/rdf-schema#comment" : [ "Calculus of variations is a field of mathematical analysis that deals with maximizing or minimizing functionals, which are mappings from a set of functions to the real numbers. Functionals are often expressed as definite integrals involving  functions and their derivatives."] } } }
