<div dir="auto"><div>You did.<div dir="auto"><br></div><div dir="auto">You forgot the trailing }</div><div dir="auto"><br></div><div dir="auto"><br></div><div dir="auto">Syntax error </div><div dir="auto"><br></div><div dir="auto">See previous email...</div><br><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Jun 17, 2023, 12:00 PM Douglas McIlroy <<a href="mailto:douglas.mcilroy@dartmouth.edu">douglas.mcilroy@dartmouth.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Google claims I just sent another unintended reply, this time unfinished.<br>
<br>
Apologies,<br>
Doug<br>
<br>
On Wed, Jun 14, 2023 at 6:42 AM Marc Donner <<a href="mailto:marc.donner@gmail.com" target="_blank" rel="noreferrer">marc.donner@gmail.com</a>> wrote:<br>
><br>
> How sparse is the 35x35 matrix? For comprehensibility would it be the best way to do it?<br>
><br>
> On Tue, Jun 13, 2023 at 9:59 PM Douglas McIlroy <<a href="mailto:douglas.mcilroy@dartmouth.edu" target="_blank" rel="noreferrer">douglas.mcilroy@dartmouth.edu</a>> wrote:<br>
>><br>
>> There may be a simple generic way to correct pic's habit of accepting<br>
>> any set of object modifiers on any object, but obeying only a<br>
>> compatible subset.<br>
>><br>
>> Pic already collects a bit vector of modifier types attached to the<br>
>> current object. If that were extended with a few more bits that<br>
>> designate the object types, the size, B, of the bit vector would be<br>
>> about 35--an easy fit in one 64-bit word. Then a BxB bit matrix could<br>
>> record both modifier/modifier incompatibilities and object/modifier<br>
>> incompatibilities. The collected bit vector needs to be tested against<br>
>> the matrix once per object definition.<br>
>><br>
>> It seems to be harder to catch duplication of modifiers, requiring<br>
>> extra code at all points where bits are set. Nevertheless, this kind<br>
>> of error also merits detection.<br>
>><br>
>> Some questions<br>
>><br>
>> Does anybody think the issue is not worth addressing?<br>
>><br>
>> Is there a better scheme than that suggested above?<br>
>><br>
>> Is the scheme adequate? It would not, for example, catch a three-way<br>
>> incompatibility that does not entail any pairwise incompatibility,<br>
>> should such an incompatibility exist.<br>
>><br>
>> Any other thoughts?<br>
>><br>
>> Doug<br>
><br>
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</blockquote></div></div></div>