{
  "@context": {
    "ex": "http://example.org/vocab#",
    "ex:p1": {
      "@type": "@id"
    }
  },
  "@graph": [
    {
      "@id": "_:b1",
      "ex:p1": "_:b2"
    },
    {
      "@id": "_:b2",
      "ex:p1": "_:b3"
    },
    {
      "@id": "_:b3"
    },
    {
      "@id": "_:b4",
      "ex:p1": "_:b5"
    },
    {
      "@id": "_:b5",
      "ex:p1": "_:b6"
    },
    {
      "@id": "_:b6"
    }
  ]
}