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<h1 class="relative group"><a id="modelos-sequncia-a-sequncia" class="header-link block pr-1.5 text-lg no-hover:hidden with-hover:absolute with-hover:p-1.5 with-hover:opacity-0 with-hover:group-hover:opacity-100 with-hover:right-full" href="#modelos-sequncia-a-sequncia"><span><svg class="" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" width="1em" height="1em" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 256"><path d="M167.594 88.393a8.001 8.001 0 0 1 0 11.314l-67.882 67.882a8 8 0 1 1-11.314-11.315l67.882-67.881a8.003 8.003 0 0 1 11.314 0zm-28.287 84.86l-28.284 28.284a40 40 0 0 1-56.567-56.567l28.284-28.284a8 8 0 0 0-11.315-11.315l-28.284 28.284a56 56 0 0 0 79.196 79.197l28.285-28.285a8 8 0 1 0-11.315-11.314zM212.852 43.14a56.002 56.002 0 0 0-79.196 0l-28.284 28.284a8 8 0 1 0 11.314 11.314l28.284-28.284a40 40 0 0 1 56.568 56.567l-28.285 28.285a8 8 0 0 0 11.315 11.314l28.284-28.284a56.065 56.065 0 0 0 0-79.196z" fill="currentColor"></path></svg></span></a>
	<span>Modelos sequência a sequência
	</span></h1>



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<p>Modelos encoder-decoder (também chamados de modelos <em>sequence-to-sequence</em>) usam ambas as partes da arquitetura Transformer. Em cada estágio, as camadas de atenção do codificador podem acessar todas as palavras da frase inicial, enquanto as camadas de atenção do decodificador podem acessar apenas as palavras posicionadas antes de uma determinada palavra na entrada.</p>
<p>O pré-treinamento desses modelos pode ser feito usando os objetivos dos modelos de codificador ou decodificador, mas geralmente envolve algo um pouco mais complexo. Por exemplo, <a href="https://huggingface.co/t5-base" rel="nofollow">T5</a> é pré-treinado substituindo trechos aleatórios de texto (que podem conter várias palavras) por uma única palavra especial de máscara, e o objetivo é prever o texto que esta palavra de máscara substitui.</p>
<p>Os modelos de sequência a sequência são mais adequados para tarefas que envolvem a geração de novas frases dependendo de uma determinada entrada, como resumo, tradução ou resposta a perguntas generativas.</p>
<p>Os representantes desta família de modelos incluem:</p>
<ul><li><a href="https://huggingface.co/transformers/model_doc/bart.html" rel="nofollow">BART</a></li>
<li><a href="https://huggingface.co/transformers/model_doc/mbart.html" rel="nofollow">mBART</a></li>
<li><a href="https://huggingface.co/transformers/model_doc/marian.html" rel="nofollow">Marian</a></li>
<li><a href="https://huggingface.co/transformers/model_doc/t5.html" rel="nofollow">T5</a></li></ul>


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