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University of Warsaw

Academic institutioneurope · pl
Official website
Research library384linked papers
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Selected work

Representative Papers

A Machine Learning Approach for Bitcoin Forecasting

Jun 29, 2023ITISE 2023

This paper addresses the problem of directional forecasting for Bitcoin price movements. Methodologically, it proposes a lightweight, price-driven ensemble framework that integrates multi-dimensional OHLC time-series features; notably, it systematically validates— for the first time—that the low price (Low) exhibits the highest contribution to directional prediction, establishing it as the core feature. The framework combines a Gated Recurrent Unit (GRU) with benchmark models into an ensemble predictor and enhances interpretability via temporal feature importance analysis. Experimental results demonstrate that using only raw price sequences achieves state-of-the-art accuracy (>62%), while non-price features—including trading volume and sentiment—exhibit negligible impact. This work delineates the effective boundary of pure time-series price modeling and establishes a novel paradigm for cryptocurrency directional forecasting: concise, robust, and interpretable.

6 citationsRead paper

Synchronization of strongly connected partial DFAs and prefix codes

Jan 13, 2021

This paper investigates the synchronization problem for strongly connected partial deterministic finite automata (partial DFAs), emphasizing their structural properties as prefix-code recognizers. Methodologically, it introduces state expansion and projection mapping techniques to establish, for the first time, computational equivalence between partial DFAs and complete DFAs regarding core synchronization problems—including the Černý conjecture, rank conjecture, and upper bounds on shortest reset words. A polynomial-time reduction algorithm is proposed, efficiently transforming the synchronization decidability problem for strongly connected partial DFAs into the corresponding problem for complete DFAs. As a result, a new upper bound on the length of shortest reset words for literal automata is derived. The contributions unify and validate the transferability of several classical synchronization conjectures across both automaton models, thereby bridging formal language theory, algebraic automata theory, and combinatorial mathematics.

6 citationsRead paper

Fair Division in a Variable Setting

Oct 18, 2024Adaptive Agents and Multi-Agent Systems

This paper studies the EF1 fairness restoration problem for indivisible resources in dynamic environments: given an existing EF1 allocation that becomes violated due to item removal or agent arrival, how to restore EF1 with minimal item reassignments while maintaining near-EF1 throughout the process? We first formalize a variable-input fair allocation model and introduce the EF1-Restoration problem. Methodologically, we develop a combinatorial optimization framework based on EF1-graph orientation: for additive utilities, we design an optimal algorithm achieving $O(m/n)$ transfers; for graphical utility models, we provide an exact algorithm. We further prove that feasibility checking for EF1 restoration under monotone binary utilities is PSPACE-complete. Our core contributions are (i) establishing the first theoretical foundation for dynamic fairness repair, and (ii) providing an efficient algorithmic framework with tight guarantees for diverse utility classes.

2 citationsRead paper

Variants of Merge-Width and Applications

Feb 27, 2026

Existing theoretical frameworks for unified graph parameters—such as treewidth, clique-width, and twin-width—lack robustness and algorithmic support. This work focuses on merge-width and its variants, establishing deep connections to sparse graph theory, neighborhood covers, and bounded expansion graph classes through characterizations based on vertex orderings and logical definability. We present the first set of equivalent definitions for merge-width, design the first non-trivial approximation algorithm running in $n^{O(1)} \cdot 2^n$ time, and demonstrate its existence in structures with constant-overlap neighborhood covers and quasi-isometric embeddings. These contributions collectively establish the robustness and algorithmic applicability of merge-width as a graph parameter.

1 citationsRead paper

Variants of Higher-Dimensional Automata

Jan 24, 2026

Higher-dimensional automata (HDA) are often too rigid in their formalism, limiting their direct applicability in modeling and reasoning. This work systematically integrates several weakened variants—such as HDA with interfaces, partial HDA, ST-automata, and relational HDA—and demonstrates, through formal language theory, automata transformations, and algebraic analysis, that these variants fall into only two distinct classes at the language level: those closed under inclusion and those that are not. The paper’s core contributions include the first proof that partial HDA satisfy a Kleene theorem and admit determinization, alongside the establishment of a unified framework that clarifies the expressive power boundaries among all considered variants. These results lay the foundational groundwork for regular expression characterizations and determinization procedures for partial HDA.

1 citationsRead paper
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