{
  "type": "project",
  "input": {
    "type": "join",
    "input": [
      {
        "type": "bgp",
        "patterns": [
          {
            "type": "pattern",
            "termType": "Quad",
            "subject": {
              "termType": "Variable",
              "value": "g"
            },
            "predicate": {
              "termType": "NamedNode",
              "value": "http://purl.org/dc/elements/1.1/publisher"
            },
            "object": {
              "termType": "Variable",
              "value": "name"
            },
            "graph": {
              "termType": "DefaultGraph",
              "value": ""
            }
          },
          {
            "type": "pattern",
            "termType": "Quad",
            "subject": {
              "termType": "Variable",
              "value": "g"
            },
            "predicate": {
              "termType": "NamedNode",
              "value": "http://purl.org/dc/elements/1.1/date"
            },
            "object": {
              "termType": "Variable",
              "value": "date"
            },
            "graph": {
              "termType": "DefaultGraph",
              "value": ""
            }
          }
        ]
      },
      {
        "type": "graph",
        "input": {
          "type": "bgp",
          "patterns": [
            {
              "type": "pattern",
              "termType": "Quad",
              "subject": {
                "termType": "Variable",
                "value": "person"
              },
              "predicate": {
                "termType": "NamedNode",
                "value": "http://xmlns.com/foaf/0.1/name"
              },
              "object": {
                "termType": "Variable",
                "value": "name"
              },
              "graph": {
                "termType": "DefaultGraph",
                "value": ""
              }
            },
            {
              "type": "pattern",
              "termType": "Quad",
              "subject": {
                "termType": "Variable",
                "value": "person"
              },
              "predicate": {
                "termType": "NamedNode",
                "value": "http://xmlns.com/foaf/0.1/mbox"
              },
              "object": {
                "termType": "Variable",
                "value": "mbox"
              },
              "graph": {
                "termType": "DefaultGraph",
                "value": ""
              }
            }
          ]
        },
        "name": {
          "termType": "Variable",
          "value": "g"
        }
      }
    ]
  },
  "variables": [
    {
      "termType": "Variable",
      "value": "name"
    },
    {
      "termType": "Variable",
      "value": "mbox"
    },
    {
      "termType": "Variable",
      "value": "date"
    }
  ]
}
