Paper detail

Searching for Disjoint Covering Systems with Precisely One Repeated Modulus

A set of arithmetical sequences $$ a_1\, (\bmod{ \,\, m_1}) \quad, \quad a_2 \, (\bmod{\,\, m_2}) \quad, \quad \dots \quad , \quad a_k \, (\bmod{\,\,m_k}) \quad \quad , $$ with $$ m_1 \leq m_2 \leq \dots \leq m_k \quad \quad , $$ is called a {\it disjoint covering system} (alias {\it exact covering system}) if every positive integer belongs to {\bf exactly} one of the sequences. Mirski, Newman, Davenport and Rado famously proved that the moduli can't all be distinct. In fact the two largest moduli must be equal, i.e. $m_{k-1}=m_k$ This raises the natural question:"How close can you get to getting distinct moduli?", in other words, can you find all such systems where all the moduli are distinct except the largest, that is repeated $r$ times, for any, specific given $r$? It turns out (conjecturally, but almost certainly) that excluding the trivial case where the smallest modulus is 2, for any number of repeats $r$, there are only finitely many such systems. Marc Berger, Alexander Felzenbaum and Aviezri Fraenkel found them all for $r$ up to $9$, and Mekmamu Zeleke and Jamie Simpson extended the list for systems up to $12$ repeats. In the present article we continue the list up to $r=32$. All our systems are correct, but we did not bother to formally prove completeness, but we know for sure that the lists are complete if the largest modulus is $\leq 600$, and we are pretty sure that they are complete.

preprint2015arXivOpen access

Signal facts

What is known right now

Open access3 authors2 topics

Next steps

Decide what to do with this paper

Use like or dislike for the fast social read. The more specific scholarly feedback stays available below when needed.

Log in to curate

Reading frame

Keep the important context close to the paper

Keep the important signals around this paper in one place: votes, save state, collection context, reviews and the metadata you need before deciding what to do next.

Institutions

Add specific reaction

Move through the context

Research map

Open full explorer

Move through nearby people, institutions, topics and adjacent work without leaving the paper page.

Building this map preview

BZPEER is loading the nearby papers, people, topics and institutions for this page.

Structured reviews

0 review(s)

ContributeLeave structured feedbackUse the review template when you have a concrete strength, concern or method question.Open review form

No structured reviews yet. High-signal critique starts here.

Work discussion

0 comment(s)

DiscussAdd a high-signal commentKeep quick notes, caveats and replication pointers separate from formal reviews.Open comment form

No discussion yet. The first strong comment sets the tone.