# Configuration space of points in Euclidean Space with fixed distances

What can we say about the configuration space of $n$ points in $\mathbb{R}^{m}$ with fixed distances between the points ?

e.g. for 2 points in $\mathbb{R}^{3}$ with fixed distance between them,the configuration space is $S^{2}$ and for 3 points in $\mathbb{R}^{3}$ with known distances between them, the configuration space is $SO(3)$.

A similar problem is to ask the configuration space of a point in $\mathbb{R}^{m}$ such that its distances from $n$ fixed points is known.

e.g. Consider a point in $\mathbb{R}^{3}$ such that its distances from 2 fixed points is $r_{1}$ and $r_{2}$. Then the point can lie on a sphere of radius $r_{1}$ around point 1 and also on a sphere of radius $r_{2}$ around point 2. Thus the configuration space is the intersection of these 2 sphere, which generically is a circle. (Correct if I'm wrong.)

What is known about these problems in general for any $n,m$ ?

• Some keywords to try: polygon spaces, configuration spaces of linkages. Nov 22, 2011 at 22:45
• Other key words are: Kapovich, Millson, Knutson, Hausmann Nov 22, 2011 at 22:49
• The setting I'm interested is slightly different from the polygon spaces, in this case every point is connected to every other by an edge, whereas in polygon spaces we've edges between consecutive points i.e. a 4-gon is a quadrilateral, but what I am interested in is a tetrahedron. After some googling it seems that what I'm looking for is configuration spaces of complete graphs. Also what I'm asking is - is it a well established theory e.g. Do we know the general configuration space for such problems. Like google tells me that for weighted graphs configuration space is some sphere. Nov 23, 2011 at 21:13

Let $G=(V,E)$ be a graph. Is the space of embeddings $p:V\rightarrow\mathbb{R}^n$ of the vertex set which preserve the distances between vertices joined by edges in $E$, modulo isometries, discrete (local rigidity), or perhaps even a single point (corresponding to the concept of global rigidity)?