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  13. <title>Adapting Proof General: A. Plans and Ideas</title>
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    45. 

  45. <tr><td valign="middle" align="left">[<a href="PG-adapting_14.html#Internals-of-Proof-General" title="Beginning of this chapter or previous chapter"> &lt;&lt; </a>]</td>
    46. 

  46. <td valign="middle" align="left">[<a href="PG-adapting_16.html#Demonstration-Instantiations" title="Next chapter"> &gt;&gt; </a>]</td>
    47. 

  47. <td valign="middle" align="left"> &nbsp; </td>
    48. 

  48. <td valign="middle" align="left"> &nbsp; </td>
    49. 

  49. <td valign="middle" align="left"> &nbsp; </td>
    50. 

  50. <td valign="middle" align="left"> &nbsp; </td>
    51. 

  51. <td valign="middle" align="left"> &nbsp; </td>
    52. 

  52. <td valign="middle" align="left">[<a href="PG-adapting.html#Top" title="Cover (top) of document">Top</a>]</td>
    53. 

  53. <td valign="middle" align="left">[<a href="PG-adapting_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
    54. 

  54. <td valign="middle" align="left">[<a href="PG-adapting_17.html#Function-Index" title="Index">Index</a>]</td>
    55. 

  55. <td valign="middle" align="left">[<a href="PG-adapting_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
    56. 

  56. </tr></table>
    57. 

  57. 

  58. <hr size="2">
    59. 

  59. <a name="Plans-and-Ideas"></a>
    60. 

  60. <a name="Plans-and-Ideas-1"></a>
    61. 

  61. <h1 class="appendix">A. Plans and Ideas</h1>
    62. 

  62. 

  63. <p>This appendix contains some tentative plans and ideas for improving
    64. 

  64. Proof General.
    65. 

  65. </p>
    66. 

  66. <p>This appendix is no longer extended: instead we keep a list of Proof
    67. 

  67. General projects on the web, and forthcoming plans and ideas in the
    68. 

  68. &lsquo;<tt>TODO</tt>&rsquo; and &lsquo;<tt>todo</tt>&rsquo; files included in the ordinary and
    69. 

  69. developers PG distributions, respectively.  Once the items mentioned
    70. 

  70. below are implemented, they will be removed from here.
    71. 

  71. </p>
    72. 

  72. <p>Please send us contributions to our wish lists, or better still, an
    73. 

  73. offer to implement something from them!
    74. 

  74. </p>
    75. 

  75. <table class="menu" border="0" cellspacing="0">
    76. 

  76. <tr><td align="left" valign="top"><a href="#Proof-by-pointing-and-similar-features">A.1 Proof by pointing and similar features</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
    77. 

  77. </td></tr>
    78. 

  78. <tr><td align="left" valign="top"><a href="#Granularity-of-atomic-command-sequences">A.2 Granularity of atomic command sequences</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">  
    79. 

  79. </td></tr>
    80. 

  80. <tr><td align="left" valign="top"><a href="#Browser-mode-for-script-files-and-theories">A.3 Browser mode for script files and theories</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">  
    81. 

  81. </td></tr>
    82. 

  82. </table>
    83. 

  83. 

  84. <hr size="6">
    85. 

  85. <a name="Proof-by-pointing-and-similar-features"></a>
    86. 

  86. <a name="Proof-by-pointing-and-similar-features-1"></a>
    87. 

  87. <h2 class="section">A.1 Proof by pointing and similar features</h2>
    88. 

  88. <a name="index-proof-by-pointing"></a>
    89. 

  89. 

  90. <p>This is a note by David Aspinall about proof by pointing and similar
    91. 

  91. features.
    92. 

  92. </p>
    93. 

  93. <p>Proof General already supports proof by pointing, and experimental
    94. 

  94. support is provided in LEGO.  We would like to extend this support to
    95. 

  95. other proof assistants.  Unfortunately, proof by pointing requires
    96. 

  96. rather heavy support from the proof assistant.  There are two aspects to
    97. 

  97. the support:
    98. 

  98. </p><ul>
    99. 

  99. <li> term structure mark-up
    100. 

  100. </li><li> proof by pointing command generation
    101. 

  101. </li></ul>
    102. 

  102. <p>Term structure mark-up is useful in itself: it allows the user to
    103. 

  103. explore the structure of a term using the mouse (the smallest
    104. 

  104. subexpression that the mouse is over is highlighted), and easily copy
    105. 

  105. subterms from the output to a proof script.
    106. 

  106. </p>
    107. 

  107. <p>Command generation for proof by pointing is usually specific to a
    108. 

  108. particular logic in use, if we hope to generate a good proof command
    109. 

  109. unambiguously for any particular click. However, Proof General could
    110. 

  110. easily be generalised to offer the user a context-sensitive choice of
    111. 

  111. next commands to apply, which may be more useful in practice, and a
    112. 

  112. worthy addition to Proof General.
    113. 

  113. </p>
    114. 

  114. <p>Implementors of new proof assistants should be encouraged to consider
    115. 

  115. supporting term-structure mark up from the start.  Command generation
    116. 

  116. should be something that the logic-implementor can specify in some way.
    117. 

  117. </p>
    118. 

  118. <p>Of the supported provers, we can certainly hope for proof-by-pointing
    119. 

  119. support from Coq, since the CtCoq proof-by-pointing code has been moved
    120. 

  120. into the Coq kernel lately.  I hope the Coq community can encourage
    121. 

  121. somebody to do this.
    122. 

  122. </p>
    123. 

  123. 

  124. <hr size="6">
    125. 

  125. <a name="Granularity-of-atomic-command-sequences"></a>
    126. 

  126. <a name="Granularity-of-atomic-command-sequences-1"></a>
    127. 

  127. <h2 class="section">A.2 Granularity of atomic command sequences</h2>
    128. 

  128. <a name="index-ACS-_0028Atomic-Command-Sequence_0029"></a>
    129. 

  129. 

  130. <p>This is a proposal by Thomas Kleymann for generalising the way Proof
    131. 

  131. General handles sequences of proof commands (see <i>Goal-save
    132. 

  132. sequences</i> in the user manual), particularly to make retraction more flexible.
    133. 

  133. </p>
    134. 

  134. <p>The blue region of a script buffer contains the initial segment of
    135. 

  135. the proof script which has been processed successfully. It consists of
    136. 

  136. atomic sequences of commands (ACS). Retraction is supported to the
    137. 

  137. beginning of every ACS. By default, every command is an ACS. But the
    138. 

  138. granularity of atomicity should be able to be adjusted.
    139. 

  139. </p>
    140. 

  140. <p>This is essential when arbitrary retraction is not supported. Usually,
    141. 

  141. after a theorem has been proved, one may only retract to the start of
    142. 

  142. the goal. One needs to mark the proof of the theorem as an ACS. At
    143. 

  143. present, support for goal-save sequences (see <i>Goal-save sequences</i> in
    144. 

  144. the user manual), has been hard wired. No other ACS are currently
    145. 

  145. supported. We propose the following to overcome this deficiency:
    146. 

  146. </p>
    147. 

  147. <dl compact="compact">
    148. 

  148. <dt> <code>proof-atomic-sequents-list</code>
    149. 

  149. <a name="index-proof_002datomic_002dsequents_002dlist"></a>
    150. 

  150. </dt>
    151. 

  151. <dd><p>is a list of instructions for setting up ACSs. Each instruction is a
    152. 

  152. list of the form <code>(<var>end</var> <var>start</var> &amp;optional
    153. 

  153. <var>forget-command</var>)</code>. <var>end</var> is a regular expression to recognise
    154. 

  154. the last command in an ACS. <var>start</var> is a function. Its input is the
    155. 

  155. last command of an ACS. Its output is a regular expression to recognise
    156. 

  156. the first command of the ACS. It is evaluated once and, starting with the
    157. 

  157. command matched by <var>end</var>, the output is
    158. 

  158. successively matched against previously processed commands until a match
    159. 

  159. occurs (or the beginning of the current buffer is reached). The region
    160. 

  160. determined by (<var>start</var>,<var>end</var>) is locked as an ACS. Optionally,
    161. 

  161. the ACS is annotated with the actual command to retract the ACS. This is 
    162. 

  162. computed by applying <var>forget-command</var> to the first and last command
    163. 

  163. of the ACS.
    164. 

  164. </p>
    165. 

  165. <p>For convenience one might also want to allow <var>start</var> to be the
    166. 

  166. symbol &lsquo;<samp>t</samp>&rsquo; as a convenient short-hand for <code>'(lambda (str)
    167. 

  167. &quot;.&quot;)</code> which always matches.
    168. 

  168. </p></dd>
    169. 

  169. </dl>
    170. 

  170. 

  171. <hr size="6">
    172. 

  172. <a name="Browser-mode-for-script-files-and-theories"></a>
    173. 

  173. <a name="Browser-mode-for-script-files-and-theories-1"></a>
    174. 

  174. <h2 class="section">A.3 Browser mode for script files and theories</h2>
    175. 

  175. 

  176. <p>This is a proposal by David Aspinall for a browser window.
    177. 

  177. </p>
    178. 

  178. <p>A browser window should provide support for browsing script files and
    179. 

  179. theories.  We should be able to inspect data in varying levels of
    180. 

  180. detail, perhaps using outlining mechanisms.  For theories, it would be
    181. 

  181. nice to query the running proof assistant.  This may require support
    182. 

  182. from the assistant in the form of output which has been specially
    183. 

  183. marked-up with an SGML like syntax, for example.
    184. 

  184. </p>
    185. 

  185. <p>A browser would be useful to:
    186. 

  186. </p><ul>
    187. 

  187. <li> Provide impoverished proof assistants with a browser
    188. 

  188. </li><li> Extend the uniform interface of Proof General to theory browsing 
    189. 

  189. </li><li> Interact closely with proof script writing
    190. 

  190. </li></ul>
    191. 

  191. <p>The last point is the most important. We should be able to integrate a
    192. 

  192. search mechanism for proofs of similar theorems, theorems containing
    193. 

  193. particular constants, etc.
    194. 

  194. </p>
    195. 

  195. 

  196. 

  197. 

  198. <hr size="6">
    199. 

  199. <table cellpadding="1" cellspacing="1" border="0">
    200. 

  200. <tr><td valign="middle" align="left">[<a href="#Plans-and-Ideas" title="Beginning of this chapter or previous chapter"> &lt;&lt; </a>]</td>
    201. 

  201. <td valign="middle" align="left">[<a href="PG-adapting_16.html#Demonstration-Instantiations" title="Next chapter"> &gt;&gt; </a>]</td>
    202. 

  202. <td valign="middle" align="left"> &nbsp; </td>
    203. 

  203. <td valign="middle" align="left"> &nbsp; </td>
    204. 

  204. <td valign="middle" align="left"> &nbsp; </td>
    205. 

  205. <td valign="middle" align="left"> &nbsp; </td>
    206. 

  206. <td valign="middle" align="left"> &nbsp; </td>
    207. 

  207. <td valign="middle" align="left">[<a href="PG-adapting.html#Top" title="Cover (top) of document">Top</a>]</td>
    208. 

  208. <td valign="middle" align="left">[<a href="PG-adapting_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
    209. 

  209. <td valign="middle" align="left">[<a href="PG-adapting_17.html#Function-Index" title="Index">Index</a>]</td>
    210. 

  210. <td valign="middle" align="left">[<a href="PG-adapting_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
    211. 

  211. </tr></table>
    212. 

  212. <p>
    213. 

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    214. 

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