{
  "id": "2411.04523",
  "version": "v1",
  "published": "2024-11-07T08:24:41.000Z",
  "updated": "2024-11-07T08:24:41.000Z",
  "title": "Countable tightness is not discretely reflexive in $σ$-compact spaces",
  "authors": [
    "István Juhász",
    "Jan van Mill"
  ],
  "comment": "7 pages",
  "categories": [
    "math.GN"
  ],
  "abstract": "Answering a question raised by V. V. Tkachuk, we present several examples of $\\sigma$-compact spaces, some only consistent and some in ZFC, that are not countably tight but in which the closure of any discrete subset is countably tight. In fact, in some of our examples the closures of all discrete subsets are even first countable.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2024-11-07T08:24:41.000Z"
    }
  ],
  "analyses": {
    "subjects": [
      "54A25",
      "54A35",
      "54D45"
    ],
    "keywords": [
      "compact spaces",
      "countable tightness",
      "discretely reflexive",
      "discrete subset",
      "countably tight"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 7,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}