{
  "aliases": null,
  "backlinks": [
    {
      "field": "defines",
      "target": "8XDYNK6TV0"
    },
    {
      "field": "uses",
      "target": "FKF9YGBKHF"
    },
    {
      "field": "uses",
      "target": "G8PGN0WQHW"
    },
    {
      "field": "about",
      "target": "G8PGN0WQHW"
    },
    {
      "field": "specializes",
      "target": "WGN82TCEF2"
    }
  ],
  "body": "\n## Summary\n\nA non-Archimedean absolute value on a field is an absolute value that satisfies the strong triangle inequality $\\abs{x + y} \\le \\max(\\abs{x}, \\abs{y})$, see the [[definition|8XDYNK6TV0]].\nIt generalizes the usual [[absolute value|0FFXKTKKQC]] of real numbers in a different direction: small elements stay small under addition.\nThe [[p-adic absolute value|WGN82TCEF2]] is the main example, and the induced metric is an [[ultrametric|A6DPR620B5]].\nThese absolute values are the same as real-valued [[valuations|B85T5VKR3M]], up to a choice of base for the exponent.\n\n## Explanations\n\n### L1 human\n\nThe usual absolute value makes $1 + 1 + \\cdots + 1$ grow without end.\nA non-Archimedean absolute value never lets a sum be larger than its largest term.\nFor the $2$-adic absolute value, a number is small when it is divisible by a high power of $2$: $\\abs{8}_2 = 1/8$ and $\\abs{3}_2 = 1$.\nThen $\\abs{8 + 16}_2 = \\abs{24}_2 = 1/8$, which is not more than the larger of $1/8$ and $1/16$.\nIn such a geometry every triangle is isosceles, and every point of a disc is a centre of it.\n",
  "commit": "5fc425f97f1f6b11da5892c2948ef8c5d8805665",
  "front": {
    "kind": "concept",
    "msc": [
      "12J25",
      "12J10"
    ],
    "name": "Non-Archimedean absolute value",
    "sources": [
      {
        "url": "https://en.wikipedia.org/wiki/Absolute_value_(algebra)"
      }
    ],
    "tag": "1H5F1BP6XS"
  },
  "kind": "concept",
  "link": "https://math2.tamnd.com/node/1H5F1BP6XS/",
  "links": null,
  "markdown": "https://math2.tamnd.com/node/1H5F1BP6XS.md",
  "msc": [
    "12J25",
    "12J10"
  ],
  "name": "Non-Archimedean absolute value",
  "prov": null,
  "role": "",
  "source": "https://github.com/tamnd/math2/blob/main/nodes/1H5/1H5F1BP6XS.md",
  "status": null,
  "tag": "1H5F1BP6XS",
  "uri": "m2://1H5F1BP6XS",
  "url": "https://math2.tamnd.com/wiki/non-archimedean-absolute-value/",
  "writing": {
    "tag": "1H5F1BP6XS",
    "kind": "concept",
    "level": "W0",
    "next": [
      {
        "what": "an inventory row",
        "note": "the row of the inventory that the node accounts for",
        "have": 0,
        "want": 1
      },
      {
        "what": "a source with a locator",
        "have": 0,
        "want": 1
      }
    ]
  }
}
