title: Uniform Cost Search algorithm pseudocode/ocaml notation
body: <p>I am just wondering if anyone can help me understand some of the notation involved in this pseudocode/ocaml notation algorithm for Uniform Cost Search.</p>
  
  <p>This is the algorithm we were given:</p>
  
  <pre><code>Input: Graph G = (V, E), Start state s, Set of goal states F
  Output: Path P ⊆ E
  1 begin
  2 let Frontier = {s};
  3 let Explored = {s};
  4 while Frontier != [] do
  5 let v ∈ Frontier, such that Path(s,v) has lowest cost;
  6 let Frontier = Frontier\{v};
  7 if v ∈ F then
  8 return Path(s,v)
  9 end
  10 else
  11 let Explored = {v}∪ Explored;
  12 let Frontier = Frontier∪{v-subscript(1), . . . , v-subscript(n)},
  where (v, v-subscript(i)) ∈ E and v-subscript(i) !∈ Explored.
  13 end
  14 end
  15 return failure;
  16 end
  </code></pre>
  
  <p>I am confused about lines 6,11 and 12. Could someone explain these lines to me? And I just want to make sure I'm right in thinking the symbol ∈ means "member of"? And finally what does the symbol ⊆ represent? Used in path output line.
  Thanks in advance to anyone that can help! :-)</p>