view, the answer is obvious: let’s apply <code>f</code> to <code>v</code>, and of course <code>(f v)</code> is of type <code>B</code>.</p>
<p>Now let’s translate this into logical statements… this gives:</p>
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<li>
<p>suppose we have two propositions <code>A</code> and <code>B</code></p>
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<li>
<p>moreover we have a proof of <code>A</code> named <code>v</code>, and a proof of <code>(==&gt; A B)</code> named <code>f</code></p>
</li>
<li>
<p>a proof of <code>B</code> is <code>(f v)</code>.</p>
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