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Small Inductive Dimension of Topological Spaces. Part II
- Source :
- Formalized Mathematics, Vol 17, Iss 3, Pp 219-222 (2009)
- Publication Year :
- 2009
- Publisher :
- Walter de Gruyter GmbH, 2009.
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Abstract
- In this paper n denotes a natural number, X denotes a set, and F1, G1 denote families of subsets of X. Let us consider X, F1. We say that F1 is finite-order if and only if: (Def. 1) There exists n such that for every G1 such that G1 ⊆ F1 and n ∈ CardG1 holds ⋂ G1 is empty. Let us consider X. Observe that there exists a family of subsets of X which is finite-order and every family of subsets of X which is finite is also finite-order. Let us considerX, F1. The functor orderF1 yielding an extended real number is defined as follows: (Def. 2)(i) For everyG1 such that orderF1+1 ∈ CardG1 andG1 ⊆ F1 holds ⋂ G1 is empty and there exists G1 such that G1 ⊆ F1 but CardG1 = orderF1+1 but ⋂ G1 is non empty or G1 is empty if F1 is finite-order, (ii) orderF1 = +∞, otherwise.
Details
- ISSN :
- 18989934 and 14262630
- Volume :
- 17
- Database :
- OpenAIRE
- Journal :
- Formalized Mathematics
- Accession number :
- edsair.doi.dedup.....8266bc7226872fcd630433ae97df5898