gistfile1.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'rdf'
require 'rdf/rdfxml'

PROGRAMMES_URL = 'http://www.bbc.co.uk/programmes'
PO = RDF::Vocabulary.new("http://purl.org/ontology/po/")

brand_pid = 'b0081dq5'
brand_rdf = "#{PROGRAMMES_URL}/#{brand_pid}.rdf"
brand_uri = RDF::URI("#{PROGRAMMES_URL}/#{brand_pid}#programme")

graph = RDF::Graph.load(brand_rdf)
episode_pids = graph.query([brand_uri, PO::episode, nil]).map do |statement|
  statement.object.basename
end

p episode_pids