Two countable, biconnected, not widely connected Hausdroff spaces
نویسندگان
چکیده
منابع مشابه
Countable Connected Spaces
Introduction, Let © be the class of all countable and connected perfectly separable Hausdorff spaces containing more than one point. I t is known that an ©-space cannot be regular or compact. Urysohn, using a complicated identification of points, has constructed the first example of an ©-space. Two ©-spaces, X and X*, more simply constructed and not involving identifications, are presented here...
متن کاملHomogeneous Countable Connected Hausdorff Spaces
In 1925, P. Urysohn gave an example of a countable connected Hausdorff space [4]. Other examples have been contributed by R. Bing [l], M. Brown [2], and E. Hewitt [3]. Relatively few of the properties of such spaces have been examined. In this paper the question of homogeneity is studied. Theorem I shows that there exists a bihomogeneous countable connected Hausdorff space. Theorems II and III ...
متن کاملGenerating connected and biconnected graphs
We focus on the algorithm underlying the main result of [6]. This is an algebraic formula to generate all connected graphs in a recursive and efficient manner. The key feature is that each graph carries a scalar factor given by the inverse of the order of its group of automorphisms. In the present paper, we revise that algorithm on the level of graphs. Moreover, we extend the result subsequentl...
متن کاملCountable connected-homogeneous graphs
A graph is connected-homogeneous if any isomorphism between finite connected induced subgraphs extends to an automorphism of the graph. In this paper we classify the countably infinite connectedhomogeneous graphs. We prove that if Γ is connected countably infinite and connected-homogeneous then Γ is isomorphic to one of: Lachlan and Woodrow’s ultrahomogeneous graphs; the generic bipartite graph...
متن کاملSpaces That Are Connected but Not Path-connected
A topological space X is called connected if it’s impossible to write X as a union of two nonempty disjoint open subsets: if X = U ∪ V where U and V are open subsets of X and U ∩ V = ∅ then one of U or V is empty. Intuitively, this means X consists of one piece. A subset of a topological space is called connected if it is connected in the subspace topology. The most fundamental example of a con...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: International Journal of Mathematics and Mathematical Sciences
سال: 1999
ISSN: 0161-1712,1687-0425
DOI: 10.1155/s016117129922251x