{
  "type": "project",
  "input": {
    "type": "extend",
    "input": {
      "type": "extend",
      "input": {
        "type": "filter",
        "input": {
          "type": "bgp",
          "patterns": [
            {
              "type": "pattern",
              "termType": "Quad",
              "subject": {
                "termType": "Variable",
                "value": "a"
              },
              "predicate": {
                "termType": "NamedNode",
                "value": "http://example.org/str"
              },
              "object": {
                "termType": "Variable",
                "value": "s1"
              },
              "graph": {
                "termType": "DefaultGraph",
                "value": ""
              }
            },
            {
              "type": "pattern",
              "termType": "Quad",
              "subject": {
                "termType": "Variable",
                "value": "b"
              },
              "predicate": {
                "termType": "NamedNode",
                "value": "http://example.org/str"
              },
              "object": {
                "termType": "Variable",
                "value": "s2"
              },
              "graph": {
                "termType": "DefaultGraph",
                "value": ""
              }
            }
          ]
        },
        "expression": {
          "type": "expression",
          "subType": "operator",
          "operator": "&&",
          "args": [
            {
              "type": "expression",
              "subType": "operator",
              "operator": "||",
              "args": [
                {
                  "type": "expression",
                  "subType": "operator",
                  "operator": "=",
                  "args": [
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "Variable",
                        "value": "a"
                      }
                    },
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "NamedNode",
                        "value": "http://example.org/s1"
                      }
                    }
                  ]
                },
                {
                  "type": "expression",
                  "subType": "operator",
                  "operator": "=",
                  "args": [
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "Variable",
                        "value": "a"
                      }
                    },
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "NamedNode",
                        "value": "http://example.org/s3"
                      }
                    }
                  ]
                }
              ]
            },
            {
              "type": "expression",
              "subType": "operator",
              "operator": "||",
              "args": [
                {
                  "type": "expression",
                  "subType": "operator",
                  "operator": "=",
                  "args": [
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "Variable",
                        "value": "b"
                      }
                    },
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "NamedNode",
                        "value": "http://example.org/s1"
                      }
                    }
                  ]
                },
                {
                  "type": "expression",
                  "subType": "operator",
                  "operator": "=",
                  "args": [
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "Variable",
                        "value": "b"
                      }
                    },
                    {
                      "type": "expression",
                      "subType": "term",
                      "term": {
                        "termType": "NamedNode",
                        "value": "http://example.org/s3"
                      }
                    }
                  ]
                }
              ]
            }
          ]
        }
      },
      "variable": {
        "termType": "Variable",
        "value": "b1"
      },
      "expression": {
        "type": "expression",
        "subType": "operator",
        "operator": "bnode",
        "args": [
          {
            "type": "expression",
            "subType": "term",
            "term": {
              "termType": "Variable",
              "value": "s1"
            }
          }
        ]
      }
    },
    "variable": {
      "termType": "Variable",
      "value": "b2"
    },
    "expression": {
      "type": "expression",
      "subType": "operator",
      "operator": "bnode",
      "args": [
        {
          "type": "expression",
          "subType": "term",
          "term": {
            "termType": "Variable",
            "value": "s2"
          }
        }
      ]
    }
  },
  "variables": [
    {
      "termType": "Variable",
      "value": "s1"
    },
    {
      "termType": "Variable",
      "value": "s2"
    },
    {
      "termType": "Variable",
      "value": "b1"
    },
    {
      "termType": "Variable",
      "value": "b2"
    }
  ]
}