Junhao Song

Large Language Models (LLMs) have demonstrated remarkable capabilities in reasoning tasks, yet their ability to execute long-horizon processes with sustained accuracy remains a fundamental challenge. This survey provides a comprehensive examination of reasoning in LLMs, spanning from foundational prompting techniques to emerging massively decomposed agentic processes. We first establish a taxonomy that categorizes reasoning approaches into three primary paradigms: prompting-based methods including Chain-of-Thought, Tree of Thoughts, and Graph of Thoughts; training-based methods encompassing reinforcement learning from human feedback, process reward models, and self-taught reasoning; and multi-agent systems that leverage decomposition and collaborative error correction. We analyze the persistent error rate problem that prevents LLMs from scaling to extended sequential tasks, where recent experiments demonstrate performance collapse beyond a few hundred dependent steps. We then examine MAKER, a breakthrough framework that achieves over one million LLM steps with zero errors through extreme task decomposition combined with multi-agent voting schemes. Our analysis reveals that massively decomposed agentic processes represent a promising paradigm shift from relying solely on improving individual model capabilities toward orchestrating ensembles of focused microagents. We synthesize empirical findings across major benchmarks including GSM8K, MATH, MMLU, and PlanBench, and identify critical open challenges including compositional generalization, error propagation mitigation, and the computational costs of inference-time scaling. This survey aims to provide researchers and practitioners with a unified perspective on the landscape of LLM reasoning and illuminate pathways toward solving problems at organizational and societal scales.

Large Language Model (LLM) agents represent a paradigm shift in artificial intelligence, combining the remarkable reasoning capabilities of foundation models with the ability to perceive environments, make decisions, and take actions autonomously. This comprehensive survey provides an in-depth examination of LLM-based agents across multiple dimensions. We first establish a formal definition of LLM agents and trace their evolution from early language models to today's sophisticated autonomous systems. We then present a novel taxonomy that organizes the field into four fundamental categories: reasoning-enhanced agents that leverage chain-of-thought and tree-structured deliberation; tool-augmented agents that extend LLM capabilities through external APIs and knowledge bases; multi-agent systems that enable collaborative problem-solving through inter-agent communication; and memory-augmented agents that maintain persistent context across interactions. For each category, we analyze representative architectures, discuss key innovations, and evaluate their relative strengths and limitations. We further examine diverse applications spanning software engineering, scientific research, embodied robotics, and web automation, supported by systematic comparisons on established benchmarks including SWE-bench, WebArena, and AgentBench. Our analysis reveals that while current agents achieve impressive performance on structured tasks, significant challenges remain in areas such as long-horizon planning, hallucination mitigation, and safe deployment. We conclude by identifying promising research directions, including neuro-symbolic integration, multi-modal perception, and human-agent collaboration frameworks, providing a roadmap for advancing this rapidly evolving field.