arXiv subjects

Yusuke Inoue

Publications and source records attributed to Yusuke Inoue.

7 recordsLinked to original sources

arXiv2026

Construction of a DFA for Computing Grundy Numbers in the Successful Derivation Games on Right-Linear Grammars

Inoue et al. have introduced the successful derivation game (SDG) on context-free grammars (CFGs), which is a generalization of classic heap-based games including subtraction games and Keyles, and shown that the least upper bound of the Grundy numbers in the SDG on a given CFG G is undecidable in general even when we restrict G to be a linear CFG. This paper shows that for the SDG on a right-linear grammar (RLG), we can construct a DFA for computing the Grundy number of a given position. In other words, for the SDG on an RLG, the set of positions with a given Grundy number c is regular. As a corollary, the least upper bound of the Grundy numbers in the SDG on a given RLG is decidable. We also investigate the complexity of computing the least upper bound of the Grundy numbers in the SDG on a given RLG, and it is shown to be PSPACE-complete.

cs.FL↗

arXiv2026

Interaction-powered Type Ibn Supernovae as a Transient PeVatron Candidate: The Case of SN 2023uqf

We investigate whether the Type Ibn supernova SN 2023uqf, reported close in time and direction to the $\sim$442 TeV IceCube alert IC-231004A, is physically consistent with a shock--circumstellar medium (CSM) interaction scenario. One-dimensional radiation-hydrodynamics calculations with {\tt STELLA} reproduce the ZTF optical light curves with a dense helium-rich CSM following $\rho_\mathrm{CSM} \propto r^{-3}$ and a CSM density parameter $D'\approx 50$. Using the shock evolution and CSM conditions obtained from the optical-fit RHD model, we model time-dependent cosmic-ray acceleration and hadronic neutrino production during the interaction phase. In our fiducial model, the inferred shock and CSM properties open a short-lived window in which multi-PeV hadron acceleration and efficient hadronic interactions can coexist. Additional loss-limited effects could reduce the high-energy cutoff, but the model provides a useful optical-to-neutrino consistency test for a transient PeVatron-like phase. After folding the predicted neutrino emission through the IceCube effective area, we obtain an expected number of $\sim10^{-5}-10^{-4}$ track-like events at $d = 723$ Mpc, depending on the alert selection. In the low-count regime, the model predicts a detection-time weighting for a rare event, and the detection time of IC-231004A falls within the high-weight interval while its energy scale is compatible with the modeled spectrum. Although a single event cannot establish a definitive association, our results show that the optically inferred environment of SN 2023uqf can satisfy the basic timing and energy requirements for a transient PeVatron-like phase in the fiducial model and illustrate how interaction-powered Type Ibn supernovae can be tested as high-energy neutrino sources.

astro-ph.HE↗

arXiv2025

Formation of circumstellar material during double-white-dwarf mergers and the early excess emissions in Type Ia supernovae

Early excess emission observed in Type Ia supernovae (SNe Ia) within $\sim1$ day of explosion provides a critical window into their progenitor systems. In the present study, we investigate formation of the circumstellar matter (CSM) in double white-dwarf (WD) mergers. We further study the interaction between the CSM and the SN ejecta. We first model the orbital evolution and super-Eddington mass transfer/ejection in the double WD systems. We then conduct hydrodynamical and light-curve (LC) simulations of the SN-CSM interaction, assuming a prompt SN Ia explosion in a context of the carbon-ignited violent merger (C-ignited VM). Our simulations show that at the moment of the merger, the binary system has the CSM distribution following $\rho_{\mathrm{CSM}}\simeq D(r/10^{14}\ \mathrm{cm})^{-3.5}\ (D\simeq 10^{-14}\text{--}10^{-13}\ \rm g\ cm^{-3})$. The simulated LCs reproduce the early flux excesses across optical to UV bands, as well as their color evolution, observed in the VM candidates, i.e., 03fg/02es-like SNe Ia. This supports that 03fg/02es-like objects originate from the VM explosions. We also discuss the case of the helium-ignited VM, which might be realized in some WD-WD mergers depending on the He content in the system. Focused here is the timing when the explosion is initiated, and we find that the explosion is initiated after the companion WD is, at least partially, tidally disrupted also in this case; we thus expect the formation of the CSM through the mass transfer phase also for the helium-ignited VM scenario.

astro-ph.HE↗

arXiv2025

Facial Expression Recognition System Using DNN Accelerator with Multi-threading on FPGA

In this paper, we implement a stand-alone facial expression recognition system on an SoC FPGA with multi-threading using a Deep learning Processor Unit (DPU). The system consists of two steps: one for face detection step and one for facial expression recognition. In the previous work, the Haar Cascade detector was run on a CPU in the face detection step due to FPGA resource limitations, but this detector is less accurate for profile and variable illumination condition images. Moreover, the previous work used a dedicated circuit accelerator, so running a second DNN inference for face detection on the FPGA would require the addition of a new accelerator. As an alternative to this approach, we run the two inferences by DNN on a DPU, which is a general-purpose CNN accelerator of the systolic array type. Our method for face detection using DenseBox and facial expression recognition using CNN on the same DPU enables the efficient use of FPGA resources while maintaining a small circuit size. We also developed a multi-threading technique that improves the overall throughput while increasing the DPU utilization efficiency. With this approach, we achieved an overall system throughput of 25 FPS and a throughput per power consumption of 2.4 times.

cs.AR↗

arXiv2025

Positive Varieties of Lattice Languages

While a language assigns a value of either `yes' or `no' to each word, a lattice language assigns an element of a given lattice to each word. An advantage of lattice languages is that joins and meets of languages can be defined as generalizations of unions and intersections. This fact also allows for the definition of positive varieties -- classes closed under joins, meets, quotients, and inverse homomorphisms -- of lattice languages. In this paper, we extend Pin's positive variety theorem, proving a one-to-one correspondence between positive varieties of regular lattice languages and pseudo-varieties of finite ordered monoids. Additionally, we briefly explore algebraic approaches to finite-state Markov chains as an application of our framework.

cs.FL↗

arXiv2024

Insights into the Properties of Type Ibn/Icn Supernovae and Their Progenitor Channels through X-ray Emission

Type Ibn/Icn supernovae (SNe Ibn/Icn), which are characterized by narrow helium or carbon lines originated in hydrogen-poor dense circumstellar medium (CSM), provide new insights into the final evolution of massive stars. While SNe Ibn/Icn are expected to emit strong X-rays through the strong SN-CSM interaction, the X-ray emission modeling effort has been limited so far. In the present study, we provide broad-band X-ray light curve (LC) predictions for SNe Ibn/Icn. We find that the soft X-ray LC provides information about the CSM compositions, while the hard X-ray LC is a robust measure of the CSM density, the explosion energy, and the ejecta mass. In addition, considering the evolution of the ionization state in the unshocked CSM, a bright soft X-ray is expected in the first few days since the explosion, which encourages rapid X-ray follow-up observations as a tool to study the nature of SNe Ibn/Icn. Applying our model to the soft X-ray LCs of SNe Ibn 2006jc and 2022ablq, we derive that the CSM potentially contains a larger fraction of carbon and oxygen for SN 2006jc than 2022ablq, highlighting the power of the soft X-ray modeling to address the nature of the CSM. We also discuss detectability and observational strategy, with which the currently operating telescopes such as NuSTAR and Swift can offer an irreplaceable opportunity to explore the nature of these enigmatic rapid transients and their still-unclarified progenitor channel(s).

astro-ph.HE↗

arXiv2024

Semidirect Product Decompositions for Periodic Regular Languages

The definition of period in finite-state Markov chains can be extended to regular languages by considering the transitions of DFAs accepting them. For example, the language $(\Sigma\Sigma)^*$ has period two because the length of a recursion (cycle) in its DFA must be even. This paper shows that the period of a regular language appears as a cyclic group within its syntactic monoid. Specifically, we show that a regular language has period $P$ if and only if its syntactic monoid is isomorphic to a submonoid of a semidirect product between a specific finite monoid and the cyclic group of order $P$. Moreover, we explore the relation between the structure of Markov chains and our result, and apply this relation to the theory of probabilities of languages. We also discuss the Krohn-Rhodes decomposition of finite semigroups, which is strongly linked to our methods.

cs.FL↗