On Wed, Dec 29, 2010 at 9:22 PM, Mark Spezzano <span dir="ltr">&lt;<a href="mailto:mark.spezzano@chariot.net.au">mark.spezzano@chariot.net.au</a>&gt;</span> wrote:<br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Duh, Sorry. Yes, there was a typo<br>
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the second one should read<br>
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If E is a combination E1 E2 then X is bound in E if and only if X is bound in E1 or is bound in E2.<br></blockquote><div><br></div><div>Seems odd.  I recommend you always work from at least three different texts.  Here&#39;s <a href="http://www.amazon.com/Lambda-Calculus-Combinators-Introduction-Roger-Hindley/dp/0521898854/ref=dp_ob_title_bk">Hindley and Seldin</a>:</div>
<div><br></div><div>&quot;An occurrence of a variable x in a term P is called</div><div><ul><li><i>bound</i> if it is in the scope of a \x in P  (NB:  using \ as lambda)</li><li><i>bound and binding</i> iff it is  the x in \x</li>
<li><i>free</i> otherwise&quot;</li></ul>The tricky question is: bound to what, exactly?</div><div><br></div><div>-Gregg</div></div>