"khi và chỉ khi" meaning in Vietnamese

{
  "head_templates": [
    {
      "args": {
        "1": "vi",
        "2": "phrases",
        "head": "",
        "sc": "",
        "sort": "",
        "tr": "",
        "ts": ""
      },
      "expansion": "khi và chỉ khi",
      "name": "head"
    },
    {
      "args": {},
      "expansion": "khi và chỉ khi",
      "name": "vi-phrase"
    }
  ],
  "lang": "Vietnamese",
  "lang_code": "vi",
  "pos": "phrase",
  "senses": [
    {
      "glosses": [
        "when and only when"
      ],
      "id": "en-khi_và_chỉ_khi-vi-phrase-wggKcjQf",
      "links": [
        [
          "when",
          "when"
        ],
        [
          "only",
          "only"
        ]
      ],
      "qualifier": "literal",
      "raw_glosses": [
        "(literal) when and only when"
      ]
    },
    {
      "categories": [
        {
          "kind": "topical",
          "langcode": "vi",
          "name": "Logic",
          "orig": "vi:Logic",
          "parents": [
            "Formal sciences",
            "Philosophy",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "vi",
          "name": "Mathematics",
          "orig": "vi:Mathematics",
          "parents": [
            "Formal sciences",
            "Sciences",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "_dis": "4 96",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "3 97",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "3 97",
          "kind": "other",
          "name": "Vietnamese entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "if and only if"
      ],
      "id": "en-khi_và_chỉ_khi-vi-phrase-69uIsb~t",
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "logic",
          "logic"
        ],
        [
          "if and only if",
          "if and only if"
        ]
      ],
      "raw_glosses": [
        "(mathematics, logic) if and only if"
      ],
      "topics": [
        "human-sciences",
        "logic",
        "mathematics",
        "philosophy",
        "sciences"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[xi˧˧ vaː˨˩ t͡ɕi˧˩ xi˧˧]",
      "tags": [
        "Hà-Nội"
      ]
    },
    {
      "ipa": "[kʰɪj˧˧ vaː˦˩ t͡ɕɪj˧˨ kʰɪj˧˧]",
      "tags": [
        "Huế"
      ]
    },
    {
      "ipa": "[xɪj˧˧ vaː˦˩ t͡ɕɪj˧˨ xɪj˧˧]",
      "tags": [
        "Huế"
      ]
    },
    {
      "ipa": "[kʰɪj˧˧ vaː˨˩ cɪj˨˩˦ kʰɪj˧˧]",
      "note": "Saigon"
    },
    {
      "ipa": "[xɪj˧˧ jaː˨˩ cɪj˨˩˦ xɪj˧˧]",
      "note": "Saigon"
    }
  ],
  "word": "khi và chỉ khi"
}

{
  "categories": [
    "Pages with 1 entry",
    "Pages with entries",
    "Vietnamese entries with incorrect language header",
    "Vietnamese lemmas",
    "Vietnamese phrases",
    "Vietnamese terms with IPA pronunciation"
  ],
  "head_templates": [
    {
      "args": {
        "1": "vi",
        "2": "phrases",
        "head": "",
        "sc": "",
        "sort": "",
        "tr": "",
        "ts": ""
      },
      "expansion": "khi và chỉ khi",
      "name": "head"
    },
    {
      "args": {},
      "expansion": "khi và chỉ khi",
      "name": "vi-phrase"
    }
  ],
  "lang": "Vietnamese",
  "lang_code": "vi",
  "pos": "phrase",
  "senses": [
    {
      "glosses": [
        "when and only when"
      ],
      "links": [
        [
          "when",
          "when"
        ],
        [
          "only",
          "only"
        ]
      ],
      "qualifier": "literal",
      "raw_glosses": [
        "(literal) when and only when"
      ]
    },
    {
      "categories": [
        "vi:Logic",
        "vi:Mathematics"
      ],
      "glosses": [
        "if and only if"
      ],
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "logic",
          "logic"
        ],
        [
          "if and only if",
          "if and only if"
        ]
      ],
      "raw_glosses": [
        "(mathematics, logic) if and only if"
      ],
      "topics": [
        "human-sciences",
        "logic",
        "mathematics",
        "philosophy",
        "sciences"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "[xi˧˧ vaː˨˩ t͡ɕi˧˩ xi˧˧]",
      "tags": [
        "Hà-Nội"
      ]
    },
    {
      "ipa": "[kʰɪj˧˧ vaː˦˩ t͡ɕɪj˧˨ kʰɪj˧˧]",
      "tags": [
        "Huế"
      ]
    },
    {
      "ipa": "[xɪj˧˧ vaː˦˩ t͡ɕɪj˧˨ xɪj˧˧]",
      "tags": [
        "Huế"
      ]
    },
    {
      "ipa": "[kʰɪj˧˧ vaː˨˩ cɪj˨˩˦ kʰɪj˧˧]",
      "note": "Saigon"
    },
    {
      "ipa": "[xɪj˧˧ jaː˨˩ cɪj˨˩˦ xɪj˧˧]",
      "note": "Saigon"
    }
  ],
  "word": "khi và chỉ khi"
}