Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
A smooth 4-manifold is a 4-manifold with a smooth structure. In dimension four, in marked contrast with lower dimensions, topological and smooth manifolds are quite different.
2
votes
Knotted projective planes and fake complex projective space
I can't think of another way to get $CP^2$ from an embedded $RP^2$ in the 4-sphere, so I would guess you are right. But why would the knottedness of the $RP^2$ imply that the $CP^2$ is exotic? After …
5
votes
Open book decompositions in dimension 4
Nice question; there's not much known in general. The signature obstruction you mention goes back to Winkelnkemper (Bull. Amer. Math. Soc. 79 (1973), 45–51) and is sufficient for simply connected $4n$ …
12
votes
Accepted
Behavior of genus function on a 4-manifold for sums
In the case that $x\cdot x \neq 0$, topological methods based on the G-signature show that the genus goes to infinity more or less quadratically in $n$. (I'll be more specific below.) This goes back t …
1
vote
Approximation theorem for Anti-Self-Dual Metrics
There are some results in this general direction, but on non-compact manifolds. See for instance Instanton approximation, periodic ASD connections, and mean dimension, by Shinichiroh Matsuo, Masaki T …
7
votes
Accepted
Distinguishing homology $S^1 \times S^2$'s which bound homotopy $S^1$'s
A standard construction would be to take a 3-manifold $Y$ given by 0-surgery on a knot $K$. If $K$ is the boundary of a slice disk $D \subset B^4$, then the complement, say $W$ of a neighborhood of $D …
3
votes
Accepted
$\pi_1$ of 4-manifolds that "look like" disk bundles
Let's take your $p$ to be prime. Then $X$ has to be simply connected, even without all of the hypotheses. Here is the argument.
From the map on $\pi_1(L) \to Z_p$ you get a map $L \to BZ_p$. This ma …
17
votes
Accepted
Handlebody decomposition of an open 4-manifold
There are not that many explicit handlebody pictures of exotic open 4-manifolds, because they get awfully complex in short order. The ones that I know of are in work of Žarko Bižaca from the mid-90's …
7
votes
Accepted
Embedding problem for 3-manifolds attacked via 4-manifolds
Since you've asked for an opinion, my answer is also an opinion. I would say that the embedding in $R^5$ is not going to be helpful. You are seeking to take $M = \partial N_i$ and `improve' the $N_i$ …
15
votes
Accepted
Characteristic class that cannot be represented by disjoint tori
In $H_2(CP^2)$, every class $nH$ where $H$ is a generator and n is odd is characteristic. However, if $n >3$, then such a class is not represented by a torus. It is not represented by a disjoint unio …
7
votes
Accepted
Invertible 2-knots in $S^4$
Q1: This is true in the topological category and unknown in the smooth setting. In the topological setting, the fundamental group of $S^4 - K_1 \# K_2$ is $G_1 *_\mathbb{Z} G_2$ where $G_i$ are the fu …
9
votes
Double ($p$-fold) coverings of $B^4$ along ribbon/slice disks
The first is in Akbulut-Kirby, Branched covers of surfaces in 4-manifolds. (Math. Ann. 252, 111-131 (1980). See the end of Section 3; it's basically explained via a single example (the square knot rib …
9
votes
Accepted
$0$-surgery of slice knots and contractible manifolds
Yes, this can be done, but requires a little care with the fundamental group. First, let me tighten up your description; one is attaching the 2-handle to $S^1 \times B^3$ along a curve $\gamma$ in its …
6
votes
Kirby diagrams of Mazur manifolds
The paper of Fickle (not the paper of Gordon to which you link) has an explicit construction for $\Sigma(3,5,19)$. It's behind a paywall but maybe you can get it from interlibrary loan or some kind so …
3
votes
4-genus of a 2-bridge link
(This is really a comment on the answer relating to concordance order.)
Since your p is even, then your 2-bridge knot is actually a link. So, while it makes sense to ask if it's a slice or ribbon l …
7
votes
Accepted
Akbulut's cork involution
The boundary of W may be described as 0-framed surgery on both components of the link you drew. The link can be drawn in a more symmetric fashion, so that it is clear that there is an involution inter …