<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Think about arithmetic mod 2. Multiplication is AND and addition is XOR. So the multiplicative identity 1 corresponds to TRUE. It just happens that the additive identity 0 works for OR, but that's not a perfect analog since 1 + 1 = 0 (2).<div><br><div><div>On Oct 28, 2011, at 9:55 AM, Carl Eastlund wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">No.  I don't see any sense in which that's a generalization of cdr.<br>In fact it's quite non-uniform; for instance, applying cdr to a<br>non-empty list produces a list one shorter.  If we want to extend cdr<br>to length 0 lists, we need to somehow produce a list of length -1.  We<br>restrict cdr from empty lists precisely because it can't be<br>generalized.  Or at least that's how I see it.<br><br>--Carl</span></blockquote></div><br></div></body></html>