helm/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>
  19 <img style="width: 95%; height: 4px;" alt="[Separator]"
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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> as soon as
  58 possible.<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>.<br>
  66         </li>
  67       </ul>
  68       <ul>
  69         <li><span style="font-weight: bold;">December 2010.</span>
  70 Permanent λδ URL acquired: <a href="http://lambda-delta.info">http://lambda-delta.info</a>
  71 (pointing at this site). <br>
  72           <span style="font-weight: bold;"></span></li>
  73       </ul>
  74       <ul>
  75         <li><span style="font-weight: bold;">November 2010.</span> <span
  76  style="font-style: italic;">Helena 0.8.1</span> is released. <br>
  77         </li>
  78       </ul>
  79       <ul>
  80         <li><span style="font-weight: bold;">September 2009.</span> <span
  81  style="font-style: italic;">Helena 0.8.0</span> is released and the <a
  82  href="implementation.html#lddl">λδ Digital Library</a> is
  83 started.<br>
  84           <span style="font-weight: bold;"></span></li>
  85       </ul>
  86       <ul>
  87         <li><span style="font-weight: bold;">June 2009.</span> <span
  88  style="font-style: italic;">Helena</span>, A <a
  89  href="implementation.html#helena">validator for </a><a
  90  href="implementation.html#helena">λδ</a><span
  91  style="font-style: italic;"></span>, <span style="font-style: italic;"></span>is
  92 available
  93 as
  94 a
  95 part
  96 of
  97 the <a href="http://helm.cs.unibo.it/">HELM</a> software. <br>
  98         </li>
  99       </ul>
 100       <span style="font-weight: bold;"></span>
 101       <ul>
 102         <li><span style="font-weight: bold;">September 2008.</span>
 103 This site is online.<br>
 104         </li>
 105       </ul>
 106       <span style="font-weight: bold;"></span>
 107       <ul>
 108         <li><span style="font-weight: bold;">July 2008.</span> <a
 109  href="documentation.html#tocl1">First journal paper on λδ</a> accepted
 110 for publication.</li>
 111       </ul>
 112       <ul>
 113         <li><span style="font-weight: bold;">July 2008.</span> First <a
 114  href="http://helm.cs.unibo.it/procedural/">procedural
 115 reconstruction</a> in <a href="http://matita.cs.unibo.it/">Matita 0.5</a>
 116 of the <a href="implementation.html#source">λδ proof scripts in
 117 Coq 7.3.1</a>.<br>
 118         </li>
 119       </ul>
 120       <ul>
 121         <li><span style="font-weight: bold;">June 2008.</span> The <a
 122  href="implementation.html#static">HTML
 123 pages of the specification of λδ in Matita 0.5</a> are online.<br>
 124           <span style="font-weight: bold;"></span></li>
 125       </ul>
 126       <ul>
 127         <li><span style="font-weight: bold;">March 2008.</span> The
 128 specification of λδ version 2 in Coq 7.3.1 begins:
 129 <!--          <ul>
 130             <li>native type assignment with new rules for application: <span
 131  style="font-style: italic;">nty</span> (it replaces <span
 132  style="font-style: italic;">ty3</span>);<br>
 133             </li>
 134             <li>parallel conversion on focalized terms: <span
 135  style="font-style: italic;">fpcs</span> (it replaces <span
 136  style="font-style: italic;"></span><span style="font-style: italic;">pc3</span>);
 137               <br>
 138             </li>
 139             <li>new weak parallel reduction on environments: <span
 140  style="font-style: italic;">wcpr</span> <span
 141  style="font-style: italic;"></span>(it is based on <span
 142  style="font-style: italic;">fpr</span> and replaces <span
 143  style="font-style: italic;">wcpr0</span>);&nbsp; <br>
 144             </li>
 145             <li>parallel reduction on focalized terms: <span
 146  style="font-style: italic;">fpr</span> and <span
 147  style="font-style: italic;">fprs</span> (they replace <span
 148  style="font-style: italic;"></span><span style="font-style: italic;"></span><span
 149  style="font-style: italic;">pr2</span>, <span
 150  style="font-style: italic;">pr3</span>); <br>
 151             </li>
 152           </ul>
 153           <ul>
 154             <li>new thinning relation: <span
 155  style="font-style: italic;">drop</span>
 156 (it replaces the old <span style="font-style: italic;">drop</span>, <span
 157  style="font-style: italic;">clear</span>, <span
 158  style="font-style: italic;">getl</span>, <span
 159  style="font-style: italic;">cimp</span>, <span
 160  style="font-style: italic;">drop1</span>);</li>
 161             <li>new shift function: <span style="font-style: italic;">shift</span>:
 162 (it
 163 replaces
 164
 165               <span style="font-style: italic;">app1</span>);</li>
 166             <li>new length function for environments: <span
 167  style="font-style: italic;">clen</span>;<br>
 168             </li>
 169             <li>new relocation function: <span
 170  style="font-style: italic;">lift</span> (it replaces old <span
 171  style="font-style: italic;">lift</span>, <span
 172  style="font-style: italic;">lift1</span>);<br>
 173             </li>
 174             <li>new term structure with polarity indicators and no
 175 distinction between binding and flat items;</li>
 176             <li>new general theory of relocation (comprises new
 177 relocation functions: <span style="font-style: italic;">s</span>, <span
 178  style="font-style: italic;">r</span>);</li>
 179             <li>we removed context-free reduction and conversion (<span
 180  style="font-style: italic;">pr0</span>, <span
 181  style="font-style: italic;">pr1</span>, <span
 182  style="font-style: italic;">pc1</span>);<br>
 183             </li>
 184             <li>we removed greedy substitution (<span
 185  style="font-style: italic;"></span><span style="font-style: italic;">csubst0</span>,
 186               <span style="font-style: italic;">csubst1</span>, <span
 187  style="font-style: italic;">fsubst0</span>, <span
 188  style="font-style: italic;">subst0</span>, <span
 189  style="font-style: italic;">subst1</span>);<br>
 190             </li>
 191             <li>we removed level indicators on environments (<span
 192  style="font-style: italic;">cbk</span>).</li>
 193           </ul>
 194 --> </li>
 195       </ul>
 196       <ul>
 197         <li><span style="font-weight: bold;">September 2007.</span>
 198 The <a href="implementation.html#dynamic">specification of λδ in
 199 Matita 0.4</a> is online.<br>
 200         </li>
 201       </ul>
 202       <ul>
 203         <li><span style="font-weight: bold;">December 2005.</span> <a
 204  href="documentation.html#bologna1">First communication on λδ</a>.<br>
 205         </li>
 206       </ul>
 207       <ul>
 208         <li><span style="font-weight: bold;">May 2004.</span> The <a
 209  href="implementation.html#source">specification of λδ in
 210 Coq 7.3.1</a> begins.<br>
 211         </li>
 212       </ul>
 213       <h3 style="text-align: right;">Visibility <img
 214  style="width: 37px; height: 37px;" alt="[Butterfly]" title="Butterfly"
 215  src="download/b4.png"></h3>
 216       <ul>
 217         <li><span style="font-weight: bold;">November 2010.</span>
 218 The <a href="http://www.google.com/">Google</a>
 219 search <span style="color: rgb(255, 0, 0);">formal system lambda delta</span>
 220 gives 8 resources about λδ as the first results.<br>
 221         </li>
 222       </ul>
 223       <ul>
 224         <li><span style="font-weight: bold;">November 2010.</span>
 225 The <a href="http://www.yahoo.com/">Yahoo</a>
 226 search <span style="color: rgb(255, 0, 0);">formal system lambda delta</span>
 227 gives 4 resources and 2 sub-resources about λδ as the first results.</li>
 228       </ul>
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 248 Guidi</a><br>
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