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<h4>Monad</h4>

<p>Algebras are related to monads and adjunctions.
Each monad gives rise to a whole category of algebras.
An 'equational theory' is called a 'T-Algebra'. This gives rise to a free -| forgetful adjunction between sets and the category of models of the theory.</p>

<ul>

<li>forgetful functor U: T-Alg -&gt; Sets</li>

<li>free functor F: Sets -&gt; T-Alg</li>

</ul>