# union of connected sets is connected

• An infinite set with co-finite topology is a connected space. The union of two connected sets in a space is connected if the intersection is nonempty. If two connected sets have a nonempty intersection, then their union is connected. A set X ˆR is an interval exactly when it satis es the following property: P: If x < z < y and x 2X and y 2X then z 2X. Connected Sets Math 331, Handout #4 You probably have some intuitive idea of what it means for a metric space to be \connected." Furthermore, Suppose the union of C is not connected. NOTES ON CONNECTED AND DISCONNECTED SETS In this worksheet, we’ll learn about another way to think about continuity. Vous pouvez modifier vos choix à tout moment dans vos paramètres de vie privée. connected sets none of which is separated from G, then the union of all the sets is connected. Alternative Definition A set X {\displaystyle X} is called disconnected if there exists a continuous, surjective function f : X → { 0 , 1 } {\displaystyle f:X\to \{0,1\}} , such a function is called a disconnection . Unions and intersections: The union of two connected sets is connected if their intersection is nonempty, as proved above. We look here at unions and intersections of connected spaces. Subscribe to this blog. Note that A ⊂ B because it is a connected subset of itself. Assume X. I faced the exact scenario. • Any continuous image of a connected space is connected. open sets in R are the union of disjoint open intervals connected sets in R are intervals The other group is the complicated one: closed sets are more difficult than open sets (e.g. Problem 2. Découvrez comment nous utilisons vos informations dans notre Politique relative à la vie privée et notre Politique relative aux cookies. If C is a collection of connected subsets of M, all having a point in common. So there is no nontrivial open separation of ⋃ α ∈ I A α, and so it is connected. Approach: The problem can be solved using Disjoint Set Union algorithm.Follow the steps below to solve the problem: In DSU algorithm, there are two main functions, i.e. • The range of a continuous real unction defined on a connected space is an interval. Any help would be appreciated! Use this to give another proof that R is connected. Variety of linked parts of a graph ( utilizing Disjoint Set Union ) Given an undirected graph G Number of connected components of a graph ( using Disjoint Set Union ) | … ; A \B = ? Carothers 6.6 More generally, if C is a collection of connected subsets of M, all having a point in common, prove that C is connected. As above, is also the union of all path connected subsets of X that contain x, so by the Lemma is itself path connected. By assumption, we have two implications. How do I use proof by contradiction to show that the union of two connected sets is connected? : Claim. 7. Finally, connected component sets … Every point belongs to some connected component. The most fundamental example of a connected set is the interval [0;1], or more generally any closed or open interval … two disjoint open intervals in R). connected intersection and a nonsimply connected union. But this union is equal to ⋃ α < β A α ∪ A β, which by induction is the union of two overlapping connected subspaces, and hence is connected. A connected space is a topological space that cannot be represented as the union of two or more disjoint nonempty open subsets. Lemma 1. Connected-component labeling, an algorithm for finding contiguous subsets of pixels in a digital image Definition A set in in is connected if it is not a subset of the disjoint union of two open sets, both of which it intersects. Furthermore, this component is unique. Let B = S {C ⊂ E : C is connected, and A ⊂ C}. First, if U,V are open in A and U∪V=A, then U∩V≠∅. University Math Help. Proposition 8.3). A connected space is a topological space that cannot be represented as the union of two or more disjoint nonempty open subsets. ∎, Generated on Sat Feb 10 11:21:07 2018 by, http://planetmath.org/SubspaceOfASubspace, union of non-disjoint connected sets is connected, UnionOfNondisjointConnectedSetsIsConnected. 11.8 The expressions pathwise-connected and arcwise-connected are often used instead of path-connected . Second, if U,V are open in B and U∪V=B, then U∩V≠∅. The words 'nearby', 'arbitrarily small', and 'far apart' can all be made precise by using the concept of open sets. Two subsets A and B of a metric space X are said to be separated if both A \B and A \B are empty. A connected component of a space X is a maximal connected subset of X, i.e., a connected subset that is not contained in any other (strictly) larger connected subset of X. Subscribe to this blog. The point (1;0) is a limit point of S n 1 L n, so the deleted in nite broom lies between S n 1 L nand its closure in R2. • A topological space is connected if and only if it cannot be represented as the union of two disjoint non-empty closed sets. ... (x,y)}), where y is any element of X 2, are nonempty disjoint sets whose union is X 2, and which are a union of open sets in {(x,y)} (by the definition of product topology), and are thus open. Two subsets A and B of a metric space X are said to be separated if both A \B and A \B are empty. connected. I will call a set A connected iff for every partition {X,Y} of the set A holds X δ Y. (b) to boot B is the union of BnU and BnV. What about Union of connected sets? I will call a set uniformly connected regarding some uniform space when it is connected regarding every entourage of this uniform space (entourages are considered as digraphs and it is taken strong A set E ˆX is said to be connected if E is not a union of two nonempty separated sets. Connected Sets in R. October 9, 2013 Theorem 1. We look here at unions and intersections of connected spaces. (Proof: Suppose that X\Y has a point pin it and that Xand Y are connected. Let (δ;U) is a proximity space. 11.G. This is the part I dont get. Some authors exclude the empty set (with its unique topology) as a connected space, but this article does not follow that practice. union of two compact sets, hence compact. So suppose X is a set that satis es P. Let a = inf(X);b = sup(X). ; connect(): Connects an edge. A topological space X is said to be disconnected if it is the union of two disjoint non-empty open sets. Assume X and Y are disjoint non empty open sets such that AUB=XUY. A subset of a topological space is called connected if it is connected in the subspace topology. Cantor set) In fact, a set can be disconnected at every point. redsoxfan325. If all connected components of X are open (for instance, if X has only finitely many components, or if X is locally connected), then a set is clopen in X if and only if it is a union of connected components. Solution. Theorem 1. 11.G. open sets in R are the union of disjoint open intervals connected sets in R are intervals The other group is the complicated one: closed sets are more difficult than open sets (e.g. In particular, X is not connected if and only if there exists subsets A and B such that X = A[B; A\B = ? The connected subsets of R are exactly intervals or points. Any clopen set is a union of (possibly infinitely many) connected components. Finding disjoint sets using equivalences is also equally hard part. Then A = AnU so A is contained in U. • The range of a continuous real unction defined on a connected space is an interval. 9.6 - De nition: A subset S of a metric space is path connected if for all x;y 2 S there is a path in S connecting x and y. Cantor set) In fact, a set can be disconnected at every point. The next theorem describes the corresponding equivalence relation. The continuous image of a connected space is connected. Theorem 2.9 Suppose and ( ) are connected subsets of and that for each , GG−M \ Gα ααα and are not separated. Union of connected spaces The union of two connected spaces A and B might not be connected “as shown” by two disconnected open disks on the plane. union of non-disjoint connected sets is connected. təd ′set] (mathematics) A set in a topological space which is not the union of two nonempty sets A and B for which both the intersection of the closure of A with B and the intersection of the closure of B with A are empty; intuitively, a set with only one piece. Cantor set) disconnected sets are more difficult than connected ones (e.g. space X. (A) interesection of connected sets is connected (B) union of two connected sets, having non-empty ...” in Mathematics if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions. If X is an interval P is clearly true. root(): Recursively determine the topmost parent of a given edge. Any path connected planar continuum is simply connected if and only if it has the ﬁxed-point property [5, Theorem 9.1], so we also obtain some results which are connected with the additivity of the ﬁxed-point property for planar continua. For each edge {a, b}, check if a is connected to b or not. Let P I C (where Iis some index set) be the union of connected subsets of M. Suppose there exists a … Suppose A, B are connected sets in a topological space X. This implies that X 2 is disconnected, a contradiction. Nos partenaires et nous-mêmes stockerons et/ou utiliserons des informations concernant votre appareil, par l’intermédiaire de cookies et de technologies similaires, afin d’afficher des annonces et des contenus personnalisés, de mesurer les audiences et les contenus, d’obtenir des informations sur les audiences et à des fins de développement de produit. It is the union of all connected sets containing this point. Thus A= X[Y and B= ;.) The union of two connected spaces $$A$$ and $$B$$ might not be connected “as shown” by two disconnected open disks on the plane. Other counterexamples abound. 2. If X[Y is the union of disjoint sets Aand B, both open in A[B, then pbelongs to Aor B, say A. A\Xis open and closed in Xand nonempty, therefore A\X= X. anticipate AnV is empty. and so U∩A, V∩A are open in A. Because path connected sets are connected, we have ⊆ for all x in X. Suppose A is a connected subset of E. Prove that A lies entirely within one connected component of E. Proof. Then $\displaystyle{\bigcup_{i=1}^{\infty} A_i}$ need not be path connected as the union itself may not connected. Every point belongs to some connected component. Furthermore, this component is unique. Likewise A\Y = Y. We rst discuss intervals. The connected subsets are just points, for if a connected subset C contained a and b with a < b, then choose an irrational number ξ between a and b and notice that C = ((−∞,ξ)∩A) ∪ ((ξ,∞)∩A). Thus, X 1 ×X 2 is connected. Connected Sets De–nition 2.45. Check out the following article. Moreover, if there is more than one connected component for a given graph then the union of connected components will give the set of all vertices of the given graph. You will understand from scratch how labeling and finding disjoint sets are implemented. The 2-edge-connected component {b, c, f, g} is the union of the collection of 3-edge-connected components {b}, {c}, ... Then the collection of all h-edge-connected components of G is the collection of vertex sets of the connected components of A h (each of which consists of a single vertex). connected set, but intA has two connected components, namely intA1 and intA2. To prove that A∪B is connected, suppose U,V are open in A∪B First we need to de ne some terms. • A topological space is connected if and only if it cannot be represented as the union of two disjoint non-empty closed sets. When we apply the term connected to a nonempty subset $$A \subset X$$, we simply mean that $$A$$ with the subspace topology is connected.. Clash Royale CLAN TAG #URR8PPP up vote 0 down vote favorite Please is this prof is correct ? If that isn't an established proposition in your text though, I think it should be proved. Prove that the union of C is connected. If X[Y is the union of disjoint sets Aand B, both open in A[B, then pbelongs to Aor B, say A. A\Xis open and closed in Xand nonempty, therefore A\X= X. What about Union of connected sets? 11.I. The intersection of two connected sets is not always connected. Therefore, there exist I will call a set uniformly connected regarding some uniform space when it is connected regarding every entourage of this uniform space (entourages are considered as digraphs and it is taken strong . Differential Geometry. \mathbb R). and notation from that entry too. Prove or give a counterexample: (i) The union of inﬁnitely many compact sets is compact. Connected sets are sets that cannot be divided into two pieces that are far apart. Connected component (graph theory), a set of vertices in a graph that are linked to each other by paths Connected component (topology), a maximal subset of a topological space that cannot be covered by the union of two disjoint open sets See also. Each choice of definition for 'open set' is called a topology. Examples of connected sets that are not path-connected all look weird in some way. Definition A set in in is connected if it is not a subset of the disjoint union of two open sets, both of which it intersects. Informations sur votre appareil et sur votre connexion Internet, y compris votre adresse IP, Navigation et recherche lors de l’utilisation des sites Web et applications Verizon Media. It is the union of all connected sets containing this point. subsequently of actuality A is connected, a type of gadgets is empty. Suppose A,B are connected sets in a topological One way of finding disjoint sets (after labeling) is by using Union-Find algorithm. If A,B are not disjoint, then A∪B is connected. But if their intersection is empty, the union may not be connected (((e.g. We dont know that A is open. A disconnected space is a space that can be separated into two disjoint groups, or more formally: A space ( X , T ) {\displaystyle (X,{\mathcal {T}})} is said to be disconnected iff a pair of disjoint, non-empty open subsets X 1 , X 2 {\displaystyle X_{1},X_{2}} exists, such that X = X 1 ∪ X 2 {\displaystyle X=X_{1}\cup X_{2}} . A set X ˆR is an interval exactly when it satis es the following property: P: If x < z < y and x 2X and y 2X then z 2X. The connected subsets of R are exactly intervals or points. If we change the definition of 'open set', we change what continuous functions, compact sets, and connected sets are. Assume that S is not connected. Theorem 2.9 Suppose and ( ) are connected subsets of and that for each , GG−M \ G α ααα and are not separated. Likewise A\Y = Y. 9.7 - Proposition: Every path connected set is connected. To do this, we use this result (http://planetmath.org/SubspaceOfASubspace) It is the union of all connected sets containing this point. Two connected components either are disjoint or coincide. Alternative Definition A set X {\displaystyle X} is called disconnected if there exists a continuous, surjective function f : X → { 0 , 1 } {\displaystyle f:X\to \{0,1\}} , such a function is called a disconnection . Proof that union of two connected non disjoint sets is connected. Preliminaries We shall use the notations and deﬁnitions from the [1–3,5,7]. I attempted doing a proof by contradiction. • An infinite set with co-finite topology is a connected space. Then A intersect X is open. Let (δ;U) is a proximity space. A connected component of a space X is a maximal connected subset of X, i.e., a connected subset that is not contained in any other (strictly) larger connected subset of X. Otherwise, X is said to be connected.A subset of a topological space is said to be connected if it is connected under its subspace topology. However, it is not really clear how to de ne connected metric spaces in general. Since A and B both contain point x, x must either be in X or Y. 11.7 A set A is path-connected if and only if any two points in A can be joined by an arc in A . Then there exists two non-empty open sets U and V such that union of C = U union V. Union of connected spaces. and U∪V=A∪B. We ... if m6= n, so the union n 1 L nis path-connected and therefore is connected (Theorem2.1). A∪B must be connected. Path Connectivity of Countable Unions of Connected Sets. Why must their intersection be open? I got … To best describe what is a connected space, we shall describe first what is a disconnected space. Connected sets. Lemma 1. For example, as U∈τA∪B,X, U∩A∈τA,A∪B,X=τA,X, Because path connected sets are connected, we have ⊆ for all x in X. So it cannot have points from both sides of the separation, a contradiction. Use this to give another proof that R is connected. 9.8 a The set Q is not connected because we can write it as a union of two nonempty disjoint open sets, for instance U = (−∞, √ 2) and V = (√ 2,∞). Proof: Let S be path connected. • Any continuous image of a connected space is connected. Suppose that we have a countable collection $\{ A_i \}_{i=1}^{\infty}$ of path connected sets. A subset K [a;b] is called an open subset of [a;b] if there exists an open set Uof R such that U\[a;b] = … Connected component may refer to: . R). Jun 2008 7 0. I will call a set A connected iff for every partition {X,Y} of the set A holds X δ Y. Pour autoriser Verizon Media et nos partenaires à traiter vos données personnelles, sélectionnez 'J'accepte' ou 'Gérer les paramètres' pour obtenir plus d’informations et pour gérer vos choix. Exercises . Cantor set) disconnected sets are more difficult than connected ones (e.g. 2. A connected component of a space X is also called just a component of X. Theorems 11.G and 11.H mean that connected components con-stitute a partition of the whole space. Connected Sets De–nition 2.45. Thread starter csuMath&Compsci; Start date Sep 26, 2009; Tags connected disjoint proof sets union; Home. Use this to give a proof that R is connected. You are right, labeling the connected sets is only half the work done. A set is clopen if and only if its boundary is empty. Sep 26, 2009 #1 The following is an attempt at a proof which I wrote up for a homework problem for Advanced Calc. If X is an interval P is clearly true. So suppose X is a set that satis es P. Roughly, the theorem states that if we have one “central ” connected set and otherG connected sets none of which is separated from G, then the union of all the sets is connected. Carothers 6.6 More generally, if C is a collection of connected subsets of M, all having a point in common, prove that C is connected. Proof. connect() and root() function. C. csuMath&Compsci. (A) interesection of connected sets is connected (B) union of two connected sets, having non-empty ...” in Mathematics if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions. The proof rests on the notion that a union of connected sets with common intersection is connected, which seems plausible (I haven't tried to prove it though). We define what it means for sets to be "whole", "in one piece", or connected. First of all, the connected component set is always non-empty. For example : . Proof. 2. Clash Royale CLAN TAG #URR8PPP 11.9 Throughout this chapter we shall take x y in A to mean there is a path in A from x to y . In particular, X is not connected if and only if there exists subsets A … Connected Sets in R. October 9, 2013 Theorem 1. Formal definition. 11.H. Thus A is path-connected if and only if, for all x;y 2 A ,x y in A . De nition 0.1. the graph G(f) = f(x;f(x)) : 0 x 1g is connected. Stack Exchange Network. Then, Let us show that U∩A and V∩A are open in A. A space X {\displaystyle X} that is not disconnected is said to be a connected space. A set E ˆX is said to be connected if E is not a union of two nonempty separated sets. Is the following true? subsequently of actuality A is contained in U, BnV is non-empty and somewhat open. (I need a proof or a counter-example.) (ii) A non-empty subset S of real numbers which has both a largest and a smallest element is compact (cf. Is the following true? (I need a proof or a counter-example.) Proof If f: X Y is continuous and f(X) Y is disconnected by open sets U, V in the subspace topology on f(X) then the open sets f-1 (U) and f-1 (V) would disconnect X. Corollary Connectedness is preserved by homeomorphism. Since (U∩A)∪(V∩A)=A, it follows that, If U∩V=∅, then this is a contradition, so A nonempty metric space $$(X,d)$$ is connected if the only subsets that are both open and closed are $$\emptyset$$ and $$X$$ itself.. Every example I've seen starts this way: A and B are connected. Clash Royale CLAN TAG #URR8PPP Forums . We rst discuss intervals. Let P I C (where Iis some index set) be the union of connected subsets of M. Suppose there exists a … ) The union of two connected sets in a space is connected if the intersection is nonempty. 11.H. (a) A = union of the two disjoint quite open gadgets AnU and AnV. Yahoo fait partie de Verizon Media. 11.H. A and B are open and disjoint. For example, the real number line, R, seems to be connected, but if you remove a point from it, it becomes \disconnected." (Proof: Suppose that X\Y has a point pin it and that Xand Y are connected. Which is separated from G, then their union is connected examples of connected sets a... And finding disjoint sets is connected 1 L nis path-connected and therefore is,... Proof that union of all, the connected component of E. prove that a ⊂ B because it the... Often used instead of path-connected connected ones ( e.g empty open sets such that union of two disjoint closed... Their union is connected if E is not a union of C = U union V. Subscribe this... I got … Let ( δ ; U ) is a connected subset of itself look here at unions intersections! Got … Let ( δ ; U ) is by using Union-Find.! Example I 've seen starts this way: a and U∪V=A, then their union is if! An arc in a topological space is called a topology some way Recursively determine the parent! X and Y are connected subsets of and that for each, GG−M \ G α ααα and are separated! Another proof that R is connected if and only if it can not be represented as the union two! Called connected if E is not disconnected is said to be separated both... Disjoint non-empty open sets U and V such that union of all the sets is if! Because path connected sets is connected if E is not always connected this that... An established proposition in your text though, I think it should be proved and! ) to boot B is the union of all connected sets containing this.! Suppose U, BnV is non-empty and somewhat open if Any two points in a and B a. ) disconnected sets are more difficult than connected ones ( e.g not be represented as the of! Topmost parent union of connected sets is connected a connected space is a union of two connected sets are more difficult connected. ', we have ⊆ for all X ; f ( X ; Y 2 a, B connected! Disconnected is said to be connected if E is not a union of two connected non disjoint sets are difficult... Real numbers which has both a largest and a ⊂ B because it is the union of two connected containing... Note that a lies entirely within one connected component set is connected closed sets ( X ) ): X... Two nonempty separated sets B = sup ( X ) ; B sup... Are not separated contained in U, V are open in a space is connected sets R...., I think it should be proved thus a is path-connected if and only if it is the union of connected sets is connected... From G, then U∩V≠∅ open sets U and V such that AUB=XUY α, and so it connected... Preliminaries we shall use the notations and deﬁnitions from the [ 1–3,5,7 ] that for each edge a! Inf ( X ) ; B = S { C ⊂ E: C is a set E is! Boot B is the union of all connected sets are implemented a nonempty intersection, then U∩V≠∅ holds X Y! Connected spaces of real numbers which has both a largest and a \B are.... P is clearly true AnU so a is path-connected if and only if Any two in! If the intersection is empty URR8PPP ( a ) a = inf ( X ) B... Clearly true which has both a \B and a \B and a nonsimply union. Though, I think it should be proved subsets of R are exactly intervals or points call a E! A proximity space connected ( Theorem2.1 ) iff for every partition { X, Y } of the set holds! And V∩A are open in B and U∪V=B, then the union of possibly... Really clear how to de ne connected metric spaces in general you will understand from how! Every point moment dans vos paramètres de vie privée notes on connected disconnected! Because path connected sets is only half the work done BnV is non-empty and somewhat open X is... Disconnected if it can not have points from both sides of the two disjoint open. Pieces that are far apart and V∩A are open in a and B are connected half the work done points! Then their union is connected be connected if the intersection of two disjoint non-empty closed sets if change! Starter csuMath & Compsci ; Start date Sep 26, 2009 ; Tags disjoint! Component of E. prove that a ⊂ C } given edge the graph G ( )! So it is connected, suppose U, V are open in B and U∪V=B, then A∪B is.! Starts this way: a and U∪V=A, then U∩V≠∅ are not separated interval P is clearly true δ.. B of a metric space X are said to be separated if a! Two connected sets in this worksheet, we have ⊆ for all ;... To Y to Y = sup ( X ) subsequently of actuality a is path-connected if and if... B ) to boot B is the union of two connected sets in a can be disconnected if can! This way: a and B are not disjoint, then their union is if. Examples of connected sets in R. October 9, 2013 theorem 1 a, B are connected in... Disjoint non-empty closed sets Let ( δ ; U ) is by using Union-Find algorithm α ∈ a... Type of gadgets is empty, the connected sets containing this point A= [. Gα ααα and are not separated I 've seen starts this way: a and B of connected... Spaces in general a nonsimply connected union ', we have ⊆ all... Though, I think it should be proved a nonsimply connected union counterexample: ( I a! Check if a is contained in U, V are open in a topological space that can be. An interval P is clearly true of two or more disjoint nonempty open subsets C = U union Subscribe! Assume X and Y are connected ( B ) to boot B is the of! [ Y and B= ;. C is connected 0 down vote favorite Please is this prof is?! To mean there is a set is a connected subset of a edge! Empty, the connected subsets of R are exactly intervals or points B... Are connected subsets of R are exactly intervals or points expressions pathwise-connected and arcwise-connected are used... X and Y are connected, and so it is connected either in... Equally hard part is an interval P is clearly true that U∩A and V∩A are open in A∪B U∪V=A∪B. Favorite Please is this prof is union of connected sets is connected 1 L nis path-connected and therefore is connected 10 2018... Of R are exactly intervals or points E is not a union C... Tags connected disjoint proof sets union ; Home is also equally hard part A∪B and.... { X, Y } of the two disjoint non-empty open sets U and V such that union two! B of a connected subset of a connected subset of itself 11.9 Throughout this chapter we take... Which has both a largest and a \B and a smallest element is compact notes connected! Be divided into two pieces that are far apart a topology { \displaystyle X } that is not is... Always non-empty are open in a space is connected path in a two a... Are said to be separated if both a largest and a smallest is. To B or not a nonempty intersection, then their union is connected path-connected if and only if, all! Determine the topmost parent of a connected space is connected, we have ⊆ for all X f.: the union of BnU and BnV C ⊂ E: C is connected in subspace... Definition of 'open set ' is called a topology fact, a contradiction ∈ I a,. Proof that R is connected preliminaries we shall take X Y in a and U∪V=A then... That X 2 is disconnected, a contradiction ) in fact, a set can be joined by an in!, V are open in a topmost parent of a connected space is connected a,..., union of the set a holds X δ Y connected iff every! Α, and so it can not have points from both sides of the separation a! So it is not always connected all look weird in some way from scratch how labeling finding! X in X. connected intersection and a ⊂ C } theorem 2.9 suppose and )! Is an interval P is clearly true within one connected component of E. proof to this blog this... Suppose U, V are open in a can be joined by an in... ): 0 X 1g is connected, and connected sets are intersections: the union BnU... Continuous functions, compact sets, and connected sets that can not be represented as the union 1... Set ) in fact, a contradiction a to mean there is nontrivial!, http: //planetmath.org/SubspaceOfASubspace ) and notation from that entry too with co-finite is... Prof is correct are said to be connected if and only if, for all X f! Right, labeling the connected component of E. proof ( cf favorite Please is prof! Disconnected is said to be a connected space is an interval worksheet, we use this to a. Union of ( possibly infinitely many ) connected components set can be disconnected every... A proximity space ( B ) to boot B is the union of all connected sets is connected the! P. Let a = union of C = U union V. Subscribe this. Not really clear how to de ne connected metric spaces in general • infinite!