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Yaé Ulrich Gaba

Publications and source records attributed to Yaé Ulrich Gaba.

At least 19 recordsLinked to original sources

Hybrid LLM-Augmented Reinforcement Learning Agents for Complex Sequential Decision Tasks

Large Language Models (LLMs) have recently shown strong capabilities in reasoning, planning, and tool-use, enabling new forms of autonomous agents. However, LLM-based agents struggle with long-horizon sequential decision tasks that require precise action optimization and environment interaction. Reinforcement Learning (RL), while effective for sequential control, often lacks the high-level abstraction and task decomposition abilities needed for complex scenarios. This paper introduces an LLM-Augmented Reinforcement Learning Agent that integrates LLM-driven planning with RL-based action optimization. The proposed architecture leverages the LLM to generate subgoals, structured plans, and contextual guidance, while the RL agent refines low-level actions through interaction with the environment. Experiments on sequential decision tasks demonstrate improved sample efficiency, higher success rates, and more coherent action trajectories compared to RL-only and LLM-only baselines. This hybrid paradigm highlights a promising direction for building more capable autonomous systems.

cs.AI↗

Detecting Money Laundering in Rwandan Mobile Money: A Machine Learning Framework

Mobile money has widened financial access across Sub-Saharan Africa and enlarged the surface for money-laundering and terrorism-financing (ML/TF) activity in ecosystems dominated by high-volume, low-value transactions. Rwanda is a case in point: several million active mobile-money users, telecom-led wallets on the MTN and Airtel networks, and a Financial Intelligence Centre (FIC) supervising transaction streams whose scale exceeds static rule-based monitoring. This paper develops and evaluates a transaction-monitoring framework aligned to the Rwandan AML/CFT regime under (i) extreme class imbalance (~0.1% prevalence), (ii) scarce and delayed labels, and (iii) bounded investigator capacity. Using SAML-D, a synthetic dataset of 9,504,852 transactions with 17 laundering typologies, we engineer account-centric behavioural features (rolling velocity, net-flow directionality, counterparty diversity, burstiness) and benchmark supervised classifiers (Logistic Regression, Random Forest, LightGBM), unsupervised anomaly detectors (Isolation Forest, Local Outlier Factor), a dense autoencoder, and a late-fusion meta-learner. Evaluation is operational: PR-AUC, recall at a calibrated ~90%-precision point, recall at top-K%, and alerts per 10,000. On the chronologically held-out test period, LightGBM attains PR-AUC = 0.0469, capturing 64 laundering cases at precision ~0.89 with 0.51 alerts per 10,000; the fusion stacker reaches PR-AUC = 0.0477 at precision ~0.91 and 0.46 alerts per 10,000, recovering 59 true positives. We map score bands to Rwanda-relevant analyst workflows and STR/SAR escalation, and outline a staged path from synthetic prototyping to real-data validation with the National Bank of Rwanda and FIC. The contribution is operational: a governance-aware pipeline and evaluation protocol calibrated to the constraints of an African mobile-money regulator, not a new algorithm.

cs.LG↗

Intelligent resource allocation in wireless networks via deep reinforcement learning

This study addresses the challenge of optimal power allocation in stochastic wireless networks by employing a Deep Reinforcement Learning (DRL) framework. Specifically, we design a Deep Q-Network (DQN) agent capable of learning adaptive power control policies directly from channel state observations, effectively bypassing the need for explicit system models. We formulate the resource allocation problem as a Markov Decision Process (MDP) and benchmark the proposed approach against classical heuristics, including fixed allocation, random assignment, and the theoretical water-filling algorithm. Empirical results demonstrate that the DQN agent achieves a system throughput of 3.88 Mbps, effectively matching the upper limit of the water fill, while outperforming the random and fixed allocation strategies by approximately 73% and 27%, respectively. Moreover, the agent exhibits emergent fairness, maintaining a Jain's Index of 0.91, and successfully optimizes the trade-off between spectral efficiency and energy consumption. These findings substantiate the efficacy of model-free DRL as a robust and scalable solution for resource management in next-generation communication systems.

cs.NI↗

On Fixed Point Theorems in Bipolar Metric Spaces Involving Polynomial-Type Contractions

In this paper, we investigate the existence and uniqueness of fixed points for self-mappings defined on bipolar metric spaces using a new class of contractive conditions, namely polynomial-type contractions. Our main results establish sufficient conditions under which a mapping on a complete bipolar metric space admits a UFP. Several illustrative examples are provided to demonstrate the applicability of our theorems, and we further show how our results generalize and improve upon existing fixed point theorems in both standard and generalized metric settings.

math.GN↗

Weak contractions via $λ$-sequences

In this note, we discuss common fixed point for a family of self mapping defined on a metric type space and satisfying a weakly contractive condition. In our development, we make use of the $λ$-sequence approach and also of a certain class of real valued maps. We derive some implications for self-mappings on quasi-pseudometric type spaces.

math.GN↗

Quasi-uniform type spaces

In this article, we introduce and investigate the concept of partial quasi-metric type space as a generalization of both partial quasi-metric and quasi-metric type spaces. We show that many important constructions studied in Künzi's theory of partial quasi-metrics can be successfully extended to these spaces. In particular, we prove that the basic theories of topology and quasi-uniformity are essentially the same for quasi-metric type spaces as for quasi-metric spaces and by extensions, to partial quasi-metric type spaces. We also prove that the Banach, Kannan, Reich and Chatterjea fixed point theorems can be successfully extended to this more general setting.

math.GN↗

Chatterjea type fixed point in Partial $b$-metric spaces

In this paper, we give and prove two Chatterjea type fixed point theorems on partial $b$-metric space. We propose an extension to the Banach contraction principle on partial $b$-metric space which was already presented by Shukla and also study some related results on the completion of a partial metric type space. In particular, we prove a joint Chatterjea-Kannan fixed point theorem. We verify the $T$-stability of Picard's iteration and conjecture the $P$ property for such maps. We also give examples to illustrate our results.

math.GN↗

Partial quasi-metric completeness via Kannan-type fixed points

In this short note, we obtain partial quasi-metric versions of Kannan's fixed point theorem for self-mappings. Moreover, we use these fixed points results to characterize a certain type of completeness in partial quasi-metric spaces. We have reported an example to support our result.

math.GN↗

Fixed point on partial metric type spaces

In this paper, we study some new fixed point results for self maps defined on partial metric type spaces. In particular, we give common fixed point theorems in the same setting. Some examples are given which illustrate the results.

math.GN↗

Startpoints via weak contractions

Startpoints (resp. endpoints) can be defined as "oriented fixed points". They arise naturally in the study of fixed for multi-valued maps defined on quasi-metric spaces. In this article, we give a new result in the startpoint theory for quasi-pseudometric spaces. The result we present is obtained via a generalized weakly contractive set-valued map.

math.GN↗

$n$-tuple fixed point in $ϕ$-ordered $G$-metric spaces

We use three seminal approaches in the study of fixed point theory, the so called $G$-metrics, multidimensional fixed points and partially ordered spaces. More precisely, we extend known results from the theory of quasi-pseudometric spaces to the $G$-metric space setting. In particular, we show the existence of $n$-tuple fixed points (resp. common $n$-tuple fixed point) for a non-decreasing mapping (resp. a pair of weakly related mappings) in a $ϕ$-ordered $G$-metric space.

math.GN↗

($2k+1)^{th}$-order Fixed points in $G$-metric spaces

We establish three major fixed-point theorems for functions satisfying an odd power type contractive condition in G-metric spaces. We first consider the case of a single mapping, followed by that of a triplet of mappings and we conclude by the case of a family of mappings. The results we obtain in this article extend similar ones already present in the literature.

math.GN↗

$η$-metric structures

In this paper, we discuss recent results about generalized metric spaces and fixed point theory. We introduce the notion of $η$-cone metric spaces, give some topological properties and prove some fixed point theorems for contractive type maps on these spaces. In particular we show that theses $η$-cone metric spaces are natural generalizations of both cone metric spaces and metric type spaces.

math.GN↗

Fixed points for weak contractions in metric type spaces

In this article, we prove some fixed point theorems in metric type spaces. This article is just a generalization some results previously proved in \cite{niyi-gaba}. In particular, we give some coupled common fixed points theorems under weak contractions. These results extend well known similar results existing in the literature.

math.GN↗

Common Coupled Fixed Point Theorems for Maps in a $T_0$-ultra-quasi-metric Space

In this article, we prove the existence of common fixed points for a pair of maps on a $q$-spherically complete $T_0$-ultra-quasi-metric space. The present article is a generalization, in the assymmetric setting of the paper of Rao et al.\cite{Rao}. The key point in the proof is the use of Zorn's lemma. We construct an appropriate chain and show that it has a maximal element, from which we extract the fixed point we are looking for. The choice of the sets, here open balls, is characteristic of this type of problems and the contraction condition are essential, specially when we are to establish the uniqueness of the fixed point

math.GN↗