---
title: Reasoning Models
seo_title: Reasoning Models — video
description: 'Five chapters on how LLMs reason: test-time compute, failure modes, latency, cost and risks when models use tools.'
keywords: reasoning models, test-time compute, chain of thought, LLM reasoning, OpenAI o1, DeepSeek R1, RLVR, GRPO, sycophancy, PRM, ORM, AI latency, TTFT, AI overthinking, specification gaming, budget forcing, extended reasoning, LLM failures
date: '2026-04-08T00:00:00+00:00'
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    <div class="s5-video-watch__crumbs"><a href="https://5sigmas.com/en/videos/">All videos</a><span>Reasoning</span><span>0:45</span></div>
    <h1>Reasoning Models</h1><p>Five chapters on how LLMs reason: test-time compute, failure modes, latency, cost and risks when models use tools.</p>
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    <div class="s5-video-watch__snippet-grid"><article><span>01</span><h2>Contents</h2></article>
<article><span>02</span><h2>1. What &quot;reasoning&quot; means for an LLM</h2><p>Which definitions of reasoning can be useful in the context of language models. The emergence of explicit reasoning-model product families, with OpenAI o1 as an important inflection point.</p></article>
<article><span>03</span><h2>2. How these systems fail</h2><p>Failure modes are not purely random: shortcuts, systematic errors, objective drift and other recurring patterns. Methods for detecting and mitigating these failures.</p></article></div>
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  <aside class="s5-video-watch__source"><div><span class="s5-eyebrow">Context and evidence</span><h2>Continue with the full article</h2><p>The chapter develops the mechanism, primary sources, limitations and connections to the rest of the series.</p></div><a class="s5-video-watch__source-link" href="https://5sigmas.com/en/series/modelos-razonadores/00_presentacion_serie/">Read the article →</a></aside>
  <section class="s5-video-watch__related" aria-labelledby="related-videos-title"><div class="s5-video-watch__section-head"><span class="s5-eyebrow">Next step</span><h2 id="related-videos-title">Related videos</h2></div><div class="s5-video-watch__related-grid"><article><a href="https://5sigmas.com/en/videos/series/modelos-razonadores/05-riesgos/"><img src="https://5sigmas.com/en/series/modelos-razonadores/05-riesgos.jpg" alt="" loading="lazy" width="1280" height="720"><span>Reasoning · 1:00</span><strong>Reasoning Risks and Production Controls</strong></a></article>
<article><a href="https://5sigmas.com/en/videos/series/modelos-razonadores/04-latencia-streaming/"><img src="https://5sigmas.com/en/series/modelos-razonadores/04-latencia-streaming.jpg" alt="" loading="lazy" width="1280" height="720"><span>Reasoning · 0:59</span><strong>Latency, Streaming and Product Design</strong></a></article>
<article><a href="https://5sigmas.com/en/videos/series/modelos-razonadores/03-test-time-compute/"><img src="https://5sigmas.com/en/series/modelos-razonadores/03-test-time-compute.jpg" alt="" loading="lazy" width="1280" height="720"><span>Reasoning · 1:00</span><strong>Test-Time Compute</strong></a></article></div></section>
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