нүүрсний тусгай ион өнхрөх бутлуур pdf
агрегат бутлуур Зимбабве. Open and closed mapsWikipedia In topology an open map is a function between two topological spaces which maps open sets to open sets That is a function → is open if for any open set U in X the image is open in Y.Likewise a closed map is a function which maps closed sets to closed sets.
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