**19**

votes

**0**answers

307 views

### Is the Poset of Graphs Automorphism-free?

For $n\geq 5$, let $\mathcal {P}_n$ be the set of all isomorphism classes of graphs with n vertices. Give this set the poset structure given by $G \le H$ if and only if $G$ is a subgraph of $H$.
...

**15**

votes

**1**answer

659 views

### Reconstruction Conjecture holds for Directed Acyclic Graphs?

Wikipedia's article on the Reconstruction Conjecture mentions that the conjecture is false for digraphs, and refers to two papers by Stockmeyer. As far as I can see, none of the counter-examples in ...

**11**

votes

**1**answer

191 views

### Reconstruction Conjecture: are almost all digraphs reconstructible?

The Reconstruction Conjecture for simple graphs remains unresolved. Most attempts I've seen at resolving the conjecture aim at proving it to be true (or partially true). I don't believe there is a ...

**11**

votes

**0**answers

375 views

### Reconstruction Conjecture and Partial 2-trees

Reconstruction conjecture says that graphs (with at least three vertices) are determined uniquely by their vertex deleted subgraphs. This conjecture is five decades old.
Searching relevant ...

**8**

votes

**1**answer

972 views

### Reconstruction conjecture: Can other decks do the job?

The standard reconstruction conjecture states that a graph is determined by its deck of vertex-deleted subgraphs.
Question: Have other decks been investigated, finding out
that only ...

**7**

votes

**4**answers

589 views

### Reconstructing graphs with vertices of degree $k$ and $k-1$

The Graph Reconstruction Conjecture claims that any simple graph with 3 or more vertices is reconstructible from its "deck" of vertex-deleted subgraphs. (A nice introduction to this problem is at this ...

**6**

votes

**1**answer

727 views

### Reconstruction Conjecture: Group theoretic formulation

As we read from wiki, informally, the reconstruction conjecture in graph theory says that graphs are determined uniquely by their subgraphs.
Is there a group-theoretic formulation of this ...

**5**

votes

**1**answer

155 views

### Reconstructing the number of Hamiltonian cycles

As is common terminology in graph reconstruction, given a graph $G$, we call a vertex deleted subgraph of $G$, a card, and call the multiset of all cards, the deck of $G$. The graph reconstruction ...

**4**

votes

**1**answer

127 views

### Edge Reconstruction Conjecture

I have seen this question asked at least once before, but not with any real answers.
I was reading about the various reconstruction conjectures and equivalents, and I saw that the reconstruction ...

**4**

votes

**1**answer

255 views

### If a graph invariant is NP-Hard, is its “deck ratio” NP-Hard as well?

This question is inspired by the Graph Reconstruction Conjecture. Suppose that $\psi$ is some graph invariant and that it is NP-Hard. There is a plethora of examples, of course. Now define ...

**3**

votes

**2**answers

145 views

### Less general edge reconstruction problem for simple graphs

Let $G$ be a simple graph. Let $E^-(G)$ denote the set of (isomorphism classes) of subgraphs of $G$ that can be obtained by deleting a single edge of $G$. Similarly, let $E^+(G)$ be the set of ...

**3**

votes

**0**answers

88 views

### Reconstructing a function from its variants that negate one argument

Call two functions $g(x_1,\ldots,x_n)$ and $h(x_1,\ldots,x_n)$ from complex numbers to complex numbers equivalent if they are the same up to the order of their arguments. Formally: there is a ...

**1**

vote

**1**answer

152 views

### edge graph reconstruction conjecture : set vs multi set

Why is the edge reconstruction conjecture stated with the deck defined as the multi set of graphs formed by deleting one edge? Can someone give an example of two graphs such that the edge deleted ...