12 papers · ranked by Valyu relevance
Otokar Grošek, Viliam Hromada, Peter Horák, James (Jong Hyuk) Park
A prefix code, a P-code, is a code where no codeword is a prefix of another codeword. In this paper, a symmetric cipher based on prefix codes is proposed. The simplicity of the design makes this cipher usable for Internet of Things applications. Our goal is to investigate the security of this cipher. A detailed…
Adam Woryna
For every natural number n ≥ 2 and every finite sequence L of natural numbers, we consider the set UDn(L) of all uniquely decodable codes over an n-letter alphabet with the sequence L as the sequence of code word lengths, as well as its subsets P Rn(L) and F Dn(L) consisting of, respectively, the prefix codes and the…
Spencer Congero, Kenneth Zeger, Jun Chen
A property of prefix codes called strong monotonicity is introduced, and it is proven that for a given source, a prefix code is optimal if and only if it is complete and strongly monotone.
Sarala M. Wimalaratne, Nick Juty, John Kunze, Greg Janée + 6 more
Compact identifiers have been widely used in biomedical informatics both formally and informally. They consist of two parts: 1) a unique prefix or namespace indicating the assigning authority and 2) a locally assigned database identifier sometimes called an accession. The former are useful to avoid global identifier…
Spencer Congero, K. Zeger
Huffman codes were invented in 1952 [9] and today are widely used in many practical data compression applications, such as for text, audio, image, and video coding. They are known to be optimal in the sense that they achieve the minimal possible expected codeword length among all prefix codes for a given finite…
Hoover H. F. Yin, Harry W. H. Wong, Mehrdad Tahernia, Russell W. F. Lai
'Russell W. F. Lai'] Abstract—The theory of multichannel prefix codes aims to generalize the classical theory of prefix codes. Although singleand two-channel prefix codes always have decoding trees, the same cannot be said when there are more than two channels. One question is of theoretical interest: Do there exist…
Roberto Bruno, Ugo Vaccaro, Igal Sason, Boris Ryabko
We consider the problem of constructing prefix-free codes in which a designated symbol, a space, can only appear at the end of codewords. We provide a linear-time algorithm to construct almost-optimal codes with this property, meaning that their average length differs from the minimum possible by at most one. We obtain…
Dominik Herrmann, Christine Arndt, Hannes Federrath
This paper is focused on privacy issues related to the prefix part of IPv6 addresses. Long-lived prefixes may introduce additional tracking opportunities for communication partners and third parties. We outline a number of prefix alteration schemes that may be deployed to maintain the unlinkability of users'…
Federica Palma, Melanie Hennart, Keith A. Jolley, Chiara Crestani + 16 more
Unified strain taxonomies are crucial for fostering international communication in microbiological research and for the epidemiological surveillance of bacterial pathogens. While multilocus sequence typing (MLST) has served as a foundation of strain taxonomy for two decades, whole genome sequencing enables more precise…
Ngo Thi Hien, Đỗ Long Vân
Alternative codes, an extension of the notion of ordinary codes, have been first introduced and considered by P. T. Huy et al. in 2004. As seen below, every alternative code, in its turn, defines an ordinary code. Such codes are called codes induced by alternative codes or alt-induced codes, for short. In this paper we…
Yuval Filmus
> Abstract. A code of the natural numbers is a uniquely-decodable binary code of the natural numbers with non-decreasing codeword lengths, which satisfies Kraft's inequality tightly. We define a natural partial order on the set of codes, and show how to construct effectively a code better than a given sequence of…
Téa S. Pusey, Andrea Presas Valencia, Adriana Signorini, Petra Kranzfelder
We developed and validated a new classroom observation protocol, Online COPUS (E-COPUS), to measure teaching and learning practices in the online learning environment. We collected COPUS and E-COPUS data from 40 STEM courses before, during the transition, and continuation of emergency remote teaching (ERT). Through…