Home » Author index

Leader, Imre


Graph Theory » Infinite Graphs

Characterizing (aleph_0,aleph_1)-graphs ★★★

Author(s): Diestel; Leader

Call a graph an $ (\aleph_0,\aleph_1) $-graph if it has a bipartition $ (A,B) $ so that every vertex in $ A $ has degree $ \aleph_0 $ and every vertex in $ B $ has degree $ \aleph_1 $.

Problem   Characterize the $ (\aleph_0,\aleph_1) $-graphs.

Keywords: binary tree; infinite graph; normal spanning tree; set theory

Posted by mdevos
updated November 24th, 2011
2 comments
Number Theory » Combinatorial N.T.

Few subsequence sums in Z_n x Z_n ★★

Author(s): Bollobas; Leader

Conjecture   For every $ 0 \le t \le n-1 $, the sequence in $ {\mathbb Z}_n^2 $ consisting of $ n-1 $ copes of $ (1,0) $ and $ t $ copies of $ (0,1) $ has the fewest number of distinct subsequence sums over all zero-free sequences from $ {\mathbb Z}_n^2 $ of length $ n-1+t $.

Keywords: subsequence sum; zero sum

Posted by mdevos
updated March 10th, 2007
add new comment
Syndicate content