"empty graph" meaning in English

{
  "forms": [
    {
      "form": "empty graphs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "empty graph (plural empty graphs)",
      "name": "en-noun"
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
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          "source": "w"
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          "source": "w"
        },
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          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Graph theory",
          "orig": "en:Graph theory",
          "parents": [
            "Mathematics",
            "Visualization",
            "Formal sciences",
            "Computing",
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          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "The empty graph with n vertices is denoted as Eₙ."
        }
      ],
      "glosses": [
        "A graph with vertices but no edges."
      ],
      "id": "en-empty_graph-en-noun-n~lnvIkz",
      "links": [
        [
          "graph theory",
          "graph theory"
        ],
        [
          "graph",
          "graph"
        ],
        [
          "vertices",
          "vertices"
        ],
        [
          "edge",
          "edge"
        ]
      ],
      "raw_glosses": [
        "(graph theory) A graph with vertices but no edges."
      ],
      "topics": [
        "graph-theory",
        "mathematics",
        "sciences"
      ]
    }
  ],
  "word": "empty graph"
}

{
  "forms": [
    {
      "form": "empty graphs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "empty graph (plural empty graphs)",
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
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      "examples": [
        {
          "text": "The empty graph with n vertices is denoted as Eₙ."
        }
      ],
      "glosses": [
        "A graph with vertices but no edges."
      ],
      "links": [
        [
          "graph theory",
          "graph theory"
        ],
        [
          "graph",
          "graph"
        ],
        [
          "vertices",
          "vertices"
        ],
        [
          "edge",
          "edge"
        ]
      ],
      "raw_glosses": [
        "(graph theory) A graph with vertices but no edges."
      ],
      "topics": [
        "graph-theory",
        "mathematics",
        "sciences"
      ]
    }
  ],
  "word": "empty graph"
}