www/lambda_delta/news.html

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  16 <h1>The Formal System λδ (lambda_delta)<br>
  17 </h1>
  18 <h2>Towards the unification of terms, types, environments and contexts</h2>
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  27       <ul>
  28         <li><a href="index.html">Foreword</a></li>
  29       </ul>
  30       <ul>
  31         <li>News</li>
  32       </ul>
  33       <ul>
  34         <li><a href="documentation.html">Papers</a></li>
  35       </ul>
  36       <ul>
  37         <li><a href="implementation.html">Resources</a><br>
  38         </li>
  39       </ul>
  40       </td>
  41       <td style="vertical-align: top; text-align: left;">
  42       <h3 style="text-align: right;">News <img
  43  style="width: 37px; height: 37px;" alt="[Butterfly]" title="Butterfly"
  44  src="download/b5.png"></h3>
  45       <ul>
  46         <li><span style="font-weight: bold;">September 2011.</span> The
  47 denomination "lambda-delta" changes to "lambda_delta".</li>
  48         <ul>
  49           <li>The character "-" is reserved in λδ textual syntax
  50 (recognized by <span style="font-style: italic;">Helena 0.8.1</span>).<br>
  51           </li>
  52           <li>Eventually, the occurrences of the character "-" will be
  53 replaced by "_" in all λδ-related identifiers.</li>
  54           <li>In particular, this refactoring involves file names and
  55 path names.</li>
  56           <li>The permanent λδ URL is sheduled to become <span
  57  style="font-style: italic;">http://lambda_delta.info</span> on
  58 December 2012.<br>
  59           </li>
  60         </ul>
  61       </ul>
  62       <ul>
  63         <li><span style="font-weight: bold;">April 2011.</span> The
  64 specification of λδ version 2 is restarted in <a
  65  href="http://matita.cs.unibo.it/">Matita 0.5</a>.</li>
  66         <ul>
  67           <li><a href="ld_basic_2.html">Here</a> is a page about the
  68 specification.<br>
  69           </li>
  70         </ul>
  71       </ul>
  72       <ul>
  73         <li><span style="font-weight: bold;">December 2010.</span>
  74 Permanent λδ URL acquired: <a href="http://lambda-delta.info">http://lambda-delta.info</a>
  75 (pointing at this site). <br>
  76           <span style="font-weight: bold;"></span></li>
  77       </ul>
  78       <ul>
  79         <li><span style="font-weight: bold;">November 2010.</span> <span
  80  style="font-style: italic;">Helena 0.8.1</span> is released. <br>
  81         </li>
  82       </ul>
  83       <ul>
  84         <li><span style="font-weight: bold;">September 2009.</span> <span
  85  style="font-style: italic;">Helena 0.8.0</span> is released and the <a
  86  href="implementation.html#lddl">λδ Digital Library</a> is
  87 started.<br>
  88           <span style="font-weight: bold;"></span></li>
  89       </ul>
  90       <ul>
  91         <li><span style="font-weight: bold;">June 2009.</span> <span
  92  style="font-style: italic;">Helena</span>, a <a
  93  href="implementation.html#helena">validator for </a><a
  94  href="implementation.html#helena">λ</a><a
  95  href="implementation.html#helena">δ version 2</a><span
  96  style="font-style: italic;"></span>, <span style="font-style: italic;"></span>is
  97 available
  98 as
  99 a
 100 part
 101 of
 102 the
 103
 104           <a href="http://helm.cs.unibo.it/">HELM</a> software. <br>
 105         </li>
 106       </ul>
 107       <span style="font-weight: bold;"></span>
 108       <ul>
 109         <li><span style="font-weight: bold;">September 2008.</span>
 110 This site is online.<br>
 111         </li>
 112       </ul>
 113       <span style="font-weight: bold;"></span>
 114       <ul>
 115         <li><span style="font-weight: bold;">July 2008.</span> <a
 116  href="documentation.html#tocl1">First journal paper on λδ</a> accepted
 117 for publication.</li>
 118       </ul>
 119       <ul>
 120         <li><span style="font-weight: bold;">July 2008.</span> First <a
 121  href="http://helm.cs.unibo.it/procedural/">procedural
 122 reconstruction</a> for <a href="http://matita.cs.unibo.it/">Matita 0.5</a>
 123 of the <a href="implementation.html#source">λδ proof scripts for
 124 Coq 7.3.1</a>.<br>
 125         </li>
 126       </ul>
 127       <ul>
 128         <li><span style="font-weight: bold;">June 2008.</span> The <a
 129  href="implementation.html#static">HTML
 130 pages of the specification of λδ version 1 for Matita 0.5</a> are
 131 online.<br>
 132           <span style="font-weight: bold;"></span></li>
 133       </ul>
 134       <ul>
 135         <li><span style="font-weight: bold;">March 2008.</span> The
 136 specification of λδ version 2 is started with Coq 7.3.1 (false start).
 137 <!--          <ul>
 138             <li>native type assignment with new rules for application: <span
 139  style="font-style: italic;">nty</span> (it replaces <span
 140  style="font-style: italic;">ty3</span>);<br>
 141             </li>
 142             <li>parallel conversion on focalized terms: <span
 143  style="font-style: italic;">fpcs</span> (it replaces <span
 144  style="font-style: italic;"></span><span style="font-style: italic;">pc3</span>);
 145               <br>
 146             </li>
 147             <li>new weak parallel reduction on environments: <span
 148  style="font-style: italic;">wcpr</span> <span
 149  style="font-style: italic;"></span>(it is based on <span
 150  style="font-style: italic;">fpr</span> and replaces <span
 151  style="font-style: italic;">wcpr0</span>);&nbsp; <br>
 152             </li>
 153             <li>parallel reduction on focalized terms: <span
 154  style="font-style: italic;">fpr</span> and <span
 155  style="font-style: italic;">fprs</span> (they replace <span
 156  style="font-style: italic;"></span><span style="font-style: italic;"></span><span
 157  style="font-style: italic;">pr2</span>, <span
 158  style="font-style: italic;">pr3</span>); <br>
 159             </li>
 160           </ul>
 161           <ul>
 162             <li>new thinning relation: <span
 163  style="font-style: italic;">drop</span>
 164 (it replaces the old <span style="font-style: italic;">drop</span>, <span
 165  style="font-style: italic;">clear</span>, <span
 166  style="font-style: italic;">getl</span>, <span
 167  style="font-style: italic;">cimp</span>, <span
 168  style="font-style: italic;">drop1</span>);</li>
 169             <li>new shift function: <span style="font-style: italic;">shift</span>:
 170 (it
 171 replaces
 172
 173               <span style="font-style: italic;">app1</span>);</li>
 174             <li>new length function for environments: <span
 175  style="font-style: italic;">clen</span>;<br>
 176             </li>
 177             <li>new relocation function: <span
 178  style="font-style: italic;">lift</span> (it replaces old <span
 179  style="font-style: italic;">lift</span>, <span
 180  style="font-style: italic;">lift1</span>);<br>
 181             </li>
 182             <li>new term structure with polarity indicators and no
 183 distinction between binding and flat items;</li>
 184             <li>new general theory of relocation (comprises new
 185 relocation functions: <span style="font-style: italic;">s</span>, <span
 186  style="font-style: italic;">r</span>);</li>
 187             <li>we removed context-free reduction and conversion (<span
 188  style="font-style: italic;">pr0</span>, <span
 189  style="font-style: italic;">pr1</span>, <span
 190  style="font-style: italic;">pc1</span>);<br>
 191             </li>
 192             <li>we removed greedy substitution (<span
 193  style="font-style: italic;"></span><span style="font-style: italic;">csubst0</span>,
 194               <span style="font-style: italic;">csubst1</span>, <span
 195  style="font-style: italic;">fsubst0</span>, <span
 196  style="font-style: italic;">subst0</span>, <span
 197  style="font-style: italic;">subst1</span>);<br>
 198             </li>
 199             <li>we removed level indicators on environments (<span
 200  style="font-style: italic;">cbk</span>).</li>
 201           </ul>
 202 --> </li>
 203       </ul>
 204       <ul>
 205         <li><span style="font-weight: bold;">September 2007.</span>
 206 The <a href="implementation.html#dynamic">specification of λδ version
 207 1 for
 208 Matita 0.4</a> is online.<br>
 209         </li>
 210       </ul>
 211       <ul>
 212         <li><span style="font-weight: bold;">December 2005.</span> <a
 213  href="documentation.html#bologna1">First communication on λδ</a>.<br>
 214         </li>
 215       </ul>
 216       <ul>
 217         <li><span style="font-weight: bold;">May 2004.</span> The <a
 218  href="implementation.html#source">specification of λδ version 1</a> is
 219 started with Coq 7.3.1.<br>
 220         </li>
 221       </ul>
 222       <h3 style="text-align: right;">Visibility <img
 223  style="width: 37px; height: 37px;" alt="[Butterfly]" title="Butterfly"
 224  src="download/b4.png"></h3>
 225       <ul>
 226         <li><span style="font-weight: bold;">February 2012.</span>
 227 The <a href="http://www.google.com/">Google</a>
 228 search for <span style="color: rgb(255, 0, 0);">formal system lambda
 229 delta</span>
 230 gives 5 resources about λδ in the first 6 results.<br>
 231         </li>
 232       </ul>
 233       <ul>
 234         <li><span style="font-weight: bold;">February 2012.</span>
 235 The <a href="http://www.yahoo.com/">Yahoo</a>
 236 search <span style="color: rgb(255, 0, 0);">formal system lambda delta</span>
 237 gives this site as the first result.</li>
 238       </ul>
 239       </td>
 240     </tr>
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 256 Last update 2012-02-21 by <a href="http://www.cs.unibo.it/%7Efguidi/">Ferruccio
 257 Guidi</a><br>
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