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In this paper, we first discuss linear codes over R and present the decomposition structure of linear codes over the mixed alphabet F q R , where R = F q + u F q + v F q + u v F q , with u2 = 1,v2 = 1, uv = vu and q = pm for odd prime p, positive integer m. Let 휃 be an automorphism on F q . Extending 휃 to Θ over R, we study skew (휃,Θ)-(λ,Γ)-constacyclic codes over F q R , where λ and Γ are units in F q and R, respectively. We also show that, the dual of a skew (휃,Θ)-(λ,Γ)-constacyclic code over F q R is a skew (휃,Θ)-(λ− 1,Γ− 1)-constacyclic code over F q R . We classify some self-dual skew (휃,Θ)-(λ,Γ)-constacyclic codes using the possible values of units of R. Also using suitable values of λ,휃,Γ and Θ, we present the structure of other linear codes over F q R . We construct a Gray map over F q R and study the Gray images of skew (휃,Θ)-(λ,Γ)-constacyclic codes over F q R . As applications of our study, we construct many good codes, among them, there are 17 optimal codes and 2 near-optimal codes. Finally, we discuss the advantages in a construction of quantum error-correcting codes (QECCs) from skew 휃-cyclic codes than from cyclic codes over F q . [ABSTRACT FROM AUTHOR]

Let p be an odd prime, q = pm, R = Fq + uFq with u2 = 1, and S = Fq + uFq + vFq + uvFq with u2 = 1, v2 = 1, uv = vu. In this paper, FqRS-cyclic codes over FqRS are studied. As an application, we present a construction of quantum error-correcting codes (QECCs) from the FqRS-cyclic codes over FqRS, which provides new QECCs. We also consider linear complementary dual (LCD) codes from the FqRS-cyclic codes over FqRS. Among others, we construct a Gray map over FqRS and discuss the Gray images of FqRS-cyclic codes over Fq.

For any prime p and positive integer m, let R be the finite commutative ring F p m + u F p m + v F p m + u v F p m , where u 2 = 0 , v 2 = 0 and u v = v u . Let λ = λ 1 + u λ 2 + v λ 3 + u v λ 4 be a unit of R, where λ 1 , λ 2 , λ 3 , λ 4 ∈ F p m and λ 1 ≠ 0 . We know that λ -constacyclic codes of length p s over R are exactly ideals of the ring R [ x ] ⟨ x p s - λ ⟩ . For all possible values of λ , we study λ -constacyclic codes of length p s over R. We also extend structures of codes from single alphabet to mixed alphabet, and determine separable constacyclic codes of length (p r , p s) over F p m R . [ABSTRACT FROM AUTHOR]

Leap et al. (2016) reduced the time complexity of the Bauer-Millward (2007) ciphertext-only attack on the Hill cipher from 풪(Ln) to 풪(Ln−1), where L is the length of the alphabet, and n is the block size. This article presents an attack that reduces the complexity to 풪(Ln−1−s), 0 ≤ s ≤ n − 1. The practical limitation on the size of s is the memory available on the computer being used for the attack. Specifically, the computer must be able to hold Ls integer arrays of length N, where N is the number of blocks of ciphertext. The key idea is not to iterate over potential rows of the decryption matrix, but to iterate over randomly chosen characters in the plaintext. This attack also admits a straightforward parallel implementation on multiple processors to further decrease the run time of the attack. [ABSTRACT FROM AUTHOR]

Recently some special type of mixed alphabet codes that generalize the standard codes has attracted much attention. Besides Z 2 Z 4 -additive codes, Z 2 Z 2 [ u ] -linear codes are introduced as a new member of such families. In this paper, we are interested in a new family of such mixed alphabet codes, i.e., codes over Z 2 Z 2 [ u 3 ] where Z 2 [ u 3 ] = { 0 , 1 , u , 1 + u , u 2 , 1 + u 2 , u + u 2 , 1 + u + u 2 } is an 8-element ring with u 3 = 0 . We study and determine the algebraic structures of linear and cyclic codes defined over this family. First, we introduce Z 2 Z 2 [ u 3 ] -linear codes and give standard forms of generator and parity-check matrices and later we present generators of both cyclic codes and their duals over Z 2 Z 2 [ u 3 ] . Further, we present some examples of optimal binary codes which are obtained through Gray images of Z 2 Z 2 [ u 3 ] -cyclic codes. [ABSTRACT FROM AUTHOR]

With the development of ICT, digital writing is becoming much more common in people's life. Differently from keyboarding alphabets directly to input English words, keyboarding Chinese character is always through typing phonetic alphabets and then identify the glyph provided by Pinyin input-method software while in this process which do not need users to produce orthography spelling, thus it is different from traditional written language production model based on handwriting process. Much of the research in this domain has found that using Pinyin input method is beneficial to Chinese characters recognition, but only a small part explored the effects of individual's Pinyin input experience on the Chinese characters production process. We ask whether using Pinyin input-method will strengthen the semantic-phonology linkage or semantic-orthography linkage in Chinese character mental lexicon. Through recording the RT and accuracy of participants completing semantic-syllable and semantic-glyph consistency judgments, the results found the accuracy of semantic-syllable consistency judgments in high Pinyin input experienced group was higher than that in low-experienced group, and RT was reversed. There were no significant differences on semantic-glyph consistency judgments between the two groups. We conclude that using Pinyin input method in Chinese digital writing can strengthen the semantic-phonology linkage while do not weakening the semantic-orthography linkage in mental lexicon at the same time, which means that Pinyin input method is beneficial to lexical processing involving Chinese cognition. [ABSTRACT FROM AUTHOR]

The goal of the paper is to prove that the problem of uniqueness of alphabetical decoding of ø- regular languages is decidable [ABSTRACT FROM AUTHOR]

As there are many use cases considered for robotics communications, the data rate variation may be very large. Some sensor applications may require very low data rate, telemetry data may require low-to-medium data rates and e.g. video application will require high data rates. On the other hand, robots may have to operate in very difficult radio propagation environments such as nuclear power plants or industrial facilities. To combat difficult propagation characteristics, an often used and well known mechanism is to use spread spectrum signal structures. Thus in this paper a novel modulation method is considered which offers the inherent signal structure and processing opportunities of spread spectrum signal and at the same time offers an easy mechanism to adapt the data rate from low to high depending on the requirement at hand thus addressing two important communication requirements for robotics. The introduction of $$m$$MFSK generated the idea of applying the given approach to other modulation methods. To further enlarge the modulation alphabet sizes (with the price of larger spectrum usage) it was realized that combining the $$m$$MFSK and $$m$$MCSK would be an interesting choice. The $$m$$MCSK- $$m$$MFSK modulation is hence considered. A method to analyze this two-component modulation is developed and the performance analyses give results for $$m$$MCSK- $$m$$MFSK modulation in AWGN and flat Rayleigh fading channels for both coherent and non-coherent receivers. The performance was also assessed with orthogonal and non-orthogonal code constructs for coherent receiver. [ABSTRACT FROM AUTHOR]

We model the secondary structure of an RNA molecule by means of a maximal non-crossing matching on a random word in a finite alphabet, where ties are only allowed between certain pairs of letters. We prove that the mean fraction of unmatched symbols does not vanish as the length of the word tends to infinity. [ABSTRACT FROM AUTHOR]

In this article, we present the dictionary of diphones (written and audio version) used by the venezuelan Spanish voice synthesizer, as well as the word list and word sequences used to build it. Through this word list, the voice synthesizer's user will have the opportunity of knowing the multiple combinations of the sounds in the Spanish spoken in Venezuela, used to create/produce the voice of the computer. On the other hand, in this article, we also give to the reader the necessary information to access, in a free way, to the voice synthesizer and also, a didactic installation-and-use manual for it. [ABSTRACT FROM AUTHOR]

We present in this paper an approach based on the use of the International Phonetic Alphabet (IPA) for content-based indexing and retrieval of multilingual audiovisual documents. The approach works even if the languages of the document are unknown. It has been validated in the context of the “Star Challenge” search engine competition organized by the Agency for Science, Technology and Research (A*STAR) of Singapore. Our approach includes the building of an IPA-based multilingual acoustic model and a dynamic programming based method for searching document segments by “IPA string spotting”. Dynamic programming allows for retrieving the query string in the document string even with a significant transcription error rate at the phone level. The methods that we developed ranked us as first and third on the monolingual (English) search task, as fifth on the multilingual search task and as first on the multimodal (audio and image) search task. [ABSTRACT FROM AUTHOR]

This paper describes universal lossless coding strategies for compressing sources on countably infinite alphabets. Classes of memoryless sources defined by an envelope condition on the marginal distribution provide benchmarks for coding techniques originating from the theory of universal coding over finite alphabets. We prove general upper bounds on minimax regret and lower bounds on minimax redundancy for such source classes. The general upper bounds emphasize the role of the normalized maximum likelihood (NML) codes with respect to minimax regret in the infinite alphabet context. Lower bounds are derived by tailoring sharp bounds on the redundancy of Krichevsky—Trofimov coders for sources over finite alphabets. Up to logarithmic (resp., constant) factors the bounds are matching for source classes defined by algebraically declining (resp., exponentially vanishing) envelopes. Effective and (almost) adaptive coding techniques are described for the collection of source classes defined by algebraically vanishing envelopes. Those results extend our knowledge concerning universal coding to contexts where the key tools from parametric inference are known to fail. [ABSTRACT FROM AUTHOR]

Let F be a finite field and b be a positive integer. A construction is presented of codes over the alphabet Fb with the following three properties: i) the codes are maximum-distance separable (MDS) over Fb, ii) they are linear over F, and iii) they have systematic generator and parity-cheek matrices over F with the smallest possible number of nonzero entries. Furthermore, for the case F = GF(2), the construction is the longest possible among all codes that satisfy properties i)–iii). [ABSTRACT FROM AUTHOR]

The article discusses the letter of Charles I to Jane Whorwood in the 17th century. Jane was the wife of Brome Whorwood who was among the small group of people that the king relied in attempting to arrange an escape while imprisoned at Carisbrooke. In his two letters to Jane, he used cipher for confidentiality reasons. It was not until the twentieth century that the cipher was deciphered in Thomas Wagstaffe's "Vindication of King Charles the Martyr."