We give a complete classification of homomorphisms from the commutator subgroup braid group on n $n$ strands to when is at least 7. In particular, we show that each non-trivial homomorphism extends an automorphism strands. This answers four questions Vladimir Lin. Our main new tool theory totally symmetric sets.

A result of Fiz Pontiveros shows that if A is a random subset of ZN where each element is chosen independently with probability N−1/2+o(1), then with high probability every Freiman homomorphism defined on A can be extended to a Freiman homomorphism on the whole of ZN . In this paper we improve the bound to CN−2/3(logN)1/3, which is best possible up to the constant factor.

In this paper, we consider the hidden subgroup problem (HSP) over the class of semi-direct product groups Zn⋊Zq. The definition of the semi-direct product depending on the choice of an homomorphism, we first analyze the different possibilities for this homomorphism in function of n and q. Then, we present a polynomial-time quantum algorithm for the case Zpr ⋊ Zp when p is an odd prime.

We show that certain canonical realizations of the complexes Hom(G,H) and Hom+(G,H) of (partial) graph homomorphisms studied by Babson and Kozlov are in fact instances of the polyhedral Cayley trick. For G a complete graph, we then characterize when a canonical projection of these complexes is itself again a complex, and exhibit several well-known objects that arise as cells or subcomplexes of ...

[2] The notation L(G) is meant to suggest the presence of the inner product on this space of functions. On a general space X with an integral, the iner product is 〈f1, f2〉 = ∫ X f1f 2. [3] The term character has different meanings in different contexts. The simplest sense is a group homomorphism to C×. However, an equally important use is for the trace of a group homomorphism ρ : G → GLn(k) fro...

A graph G is said to be hom-idempotent if there is a homomorphism from G2 to G, and weakly hom-idempotent if for some n ≥ 1 there is a homomorphism from Gn+1 to Gn . We characterize both classes of graphs in terms of a special class of Cayley graphs called normal Cayley graphs. This allows us to construct, for any integer n, a Cayley graph G such that Gn+1 → Gn 6→ Gn−1, answering a question of ...

...

Let Gn,k denote the Kneser graph whose vertices are the n-element subsets of a (2n + k)-element set and whose edges are the disjoint pairs. In this paper we prove that for any non-negative integer s there is no graph homomorphism from G4,2 to G4s+1,2s+1. This confirms a conjecture of Stahl in a special case.

Finite State Machine (FSM) model is widely used in the construction of binary convolutional codes. If Z2 = {0, 1} is the binary mod-2 addition group and Z n 2 is the n-times direct product of Z2, then a binary convolutional encoder, with rate k n < 1 and memory m, is a FSM with Z2 as inputs group, Z n 2 as outputs group and Z m 2 as states group. The next state mapping ν : Z2⊕Z m 2 → Z m 2 is a...

Proof. The intersection P of all subfields of F is a field by Exercise 1.4. Consider the ring homomorphism φ : Z → F given by φ(n) = n · 1. Since any subfield contains 1 and is closed under addition, imφ is contained in P . If Char F = p 6= 0 then imφ is isomorphic to Z/pZ = Fp. Since this is a field, we have P = imφ ∼= Fp. If Char F = 0 then φ is injective. Define φ̂ : Q → F by φ̂(m/n) = φ(m)/φ(...