arXiv subjects

Ryosuke Sakai

Publications and source records attributed to Ryosuke Sakai.

4 recordsLinked to original sources

arXiv2025

Egalitarian-equivalent and strategy-proof mechanisms in homogeneous multi-object allocation problems

We study the problem of allocating homogeneous indivisible objects among agents with money. In particular, we investigate the relationship between egalitarian-equivalence (Pazner and Schmeidler, 1978), as a fairness concept, and efficiency under agents' incentive constraints. As a first result, we characterize the class of mechanisms that satisfy egalitarian-equivalence, strategy-proofness, individual rationality, and no subsidy. Our characterization reveals a strong tension between egalitarian-equivalence and efficiency: under these properties, objects are allocated only in limited cases. To address this limitation, we replace strategy-proofness with the weaker incentive property non-obvious manipulability (Troyan and Morrill, 2020). We show that this relaxation allows us to design mechanisms that achieve efficiency while still ensuring egalitarian-equivalence. Furthermore, under efficiency, we identify the agent-welfare-optimal mechanism in the characterized class.

econ.TH↗

arXiv2025

AudioBERTScore: Objective Evaluation of Environmental Sound Synthesis Based on Similarity of Audio embedding Sequences

We propose a novel objective evaluation metric for synthesized audio in text-to-audio (TTA), aiming to improve the performance of TTA models. In TTA, subjective evaluation of the synthesized sound is an important, but its implementation requires monetary costs. Therefore, objective evaluation such as mel-cepstral distortion are used, but the correlation between these objective metrics and subjective evaluation values is weak. Our proposed objective evaluation metric, AudioBERTScore, calculates the similarity between embedding of the synthesized and reference sounds. The method is based not only on the max-norm used in conventional BERTScore but also on the $p$-norm to reflect the non-local nature of environmental sounds. Experimental results show that scores obtained by the proposed method have a higher correlation with subjective evaluation values than conventional metrics.

cs.SD↗

arXiv2021

Transferring quantum information between a quantum system with limited control and a quantum computer

We consider a hybrid quantum system consisting of a qubit system continuously evolving according to its fixed own Hamiltonian and a quantum computer. The qubit system couples to a quantum computer through a fixed interaction Hamiltonian, which can only be switched on and off. We present quantum algorithms to approximately transfer quantum information between the qubit system with limited control and the quantum computer under this setting. Our algorithms are programmed by the gate sequences in a closed formula for a given interface interaction Hamiltonian.

quant-ph↗

arXiv2019

Robust controllability of two-qubit Hamiltonian dynamics

Quantum gates (unitary gates) on physical systems are usually implemented by controlling the Hamiltonian dynamics. When full descriptions of the Hamiltonians parameters is available, the set of implementable quantum gates is easily characterised by quantum control theory. In many real systems, however, the Hamiltonians may include unknown parameters due to the difficulty of precise measurements or instability of the system. In this paper, we consider the situation that some parameters of the Hamiltonian are unknown, but we still want to perform a robust control of a quantum gate irrespectively to the unknown parameters. The existence of such control was previously shown in single-qubit systems, and a constructive method was developed for two-qubit systems provided full single-qubit controls are available. We analytically investigate the robust controllability of two-qubit systems, and apply Lie algebraic approaches to handle the cases where only controlling one of the two qubits is allowed. We also use numerical approaches for these problems since our analytical approaches does not work in some systems.

quant-ph↗