l.json

{
  "domains": [
    {
      "id": "d1",
      "value": [
        0,
        1
      ]
    }
  ],
  "constraints": [
    {
      "id": "c1",
      "value": [
        [
          1,
          0
        ],
        [
          0,
          2
        ]
      ]
    }
  ],
  "nodes": [
    {
      "id": "x1",
      "domain": "d1"
    },
    {
      "id": "x2",
      "domain": "d1"
    },
    {
      "id": "x3",
      "domain": "d1"
    },
    {
      "id": "x4",
      "domain": "d1"
    }
  ],
  "edges": [
    {
      "source": "x1",
      "target": "x2",
      "constraint": "c1"
    },
    {
      "source": "x2",
      "target": "x3",
      "constraint": "c1"
    },
    {
      "source": "x3",
      "target": "x4",
      "constraint": "c1"
    },
    {
      "source": "x4",
      "target": "x1",
      "constraint": "c1"
    }
  ]
}