mirror of https://github.com/texmacs/doc.git
127 lines
6.5 KiB
Tcl
127 lines
6.5 KiB
Tcl
<TeXmacs|1.99.8>
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<style|<tuple|tmdoc|english|old-spacing>>
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<\body>
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<tmdoc-title|Common errors and syntax correction>
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By default, the semantic editing mode \Punderstands\Q most classical
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mathematical notations. This is achieved through the use of a carefully
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designed grammar for mainstream mathematics. Obviously, the use of a fixed
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grammar may cause the following problems:
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<\itemize>
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<item>Mathematical formulas frequently contain <em|ad hoc> notations. For
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instance, the formulas might contain some text or meaningful whitespace.
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Another example of an <em|ad hoc> notation is the sign sequence
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<math|++-+-+>. In such cases, the user should <hlink|explicitly
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annotate|man-semantic-annotation.en.tm> the appropriate parts of the
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formula in order to make them semantically meaningful.
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<item>The <TeXmacs> grammar used for the interpretation of mathematical
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formulas may be incomplete or inadequate for certain situations. It is
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possible to customize or extend the grammar using the standard <TeXmacs>
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macro mechanism. Notations for specific areas may be grouped together in
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dedicated style packages.
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</itemize>
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Besides these intrinsically hard to avoid problems, the following common
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and \Peasy-to-make\Q mistakes are a further source of trouble for
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associating semantics to mathematical formulas:
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<\itemize>
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<item>Since <TeXmacs> is a wysiwyg editor, some of the structure of the
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document is invisible for the user. For instance, the presence of a
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mathematical formula <math|x+y> is indicated through the use of an italic
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slant and special spacing. However, in the formula
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<math|f<around*|(|x|)>> it is easy to type the closing bracket outside
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the formula, with no visual difference.
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<item>Various mathematical notations are visually ambiguous. For
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instance, <math|a*<around*|(|b+c|)>> would usually be understood as
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<math|a\<cdot\><around*|(|b+c|)>>, whereas <math|f<around*|(|x+y|)>>
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rather corresponds to a function application. In the semantic editing
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mode, the user is expected to resolve this ambiguity by hand by entering
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multiplications using <key|*> and spaces using <key|space>. The
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multiply/apply ambiguity is one of the main sources of syntax errors,
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since many users do not pay attention to invisible differences.
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Similarly, the <math|\<wedge\>> glyph could be the \Plogical and\Q or the
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\Pwedge product\Q. This \Phomoglyph\Q issue will be addressed in more
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detail in the section on the <hlink|semantics of mathematical
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symbols|man-semantics-symbols.en.tm>.\
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<item>It could be that a text was originally written in <LaTeX> or an old
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version of <TeXmacs>. In that case, the document contains no special
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indication on matching brackets or the scopes of big operators. For
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instance, in the formula <math|<around*|[|x,y|[>>, should we interpret
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the second bracket as a closing bracket? This is indeed the standard
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french notation for an interval with an open right end. More generally,
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all problems that we have mentioned so far tend to be present
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simultaneously when trying to associate semantics to existing documents.
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</itemize>
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After activation of the semantic editing mode, you may check whether a
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formula is correct by positioning your cursor inside it and looking at the
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color of the bounding box of the <hlink|semantic
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focus|man-semantics.en.tm#semantic-focus>: a<nbsp>green color corresponds
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to a correct formula and a<nbsp>red color indicates an error in the
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formula. Alternatively, assuming that the focus is on a mathematical
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formula, you may select <menu|Focus|Preferences|Highlight incorrect
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formulas>, in which all incorrect formulas are highlighted inside red
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boxes.
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For the second kind of \Peasy-to-make\Q errors, <TeXmacs> includes an
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automatic syntax corrector. Assuming that your cursor is inside a formula,
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you may use <menu|Edit|Correct|Correct all> for the correction of all
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formulas in your document, or the correction of the current selection. If
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the versioning tool is activated, then you may use
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<menu|Edit|Correct|Correct manually> to show the differences between the
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original and the corrected versions. You may then use the versioning tool
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to go through these differences and select the preferred versions.
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The precise algorithms which are used for the correction may be enabled or
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disabled from <menu|Edit|Preferences|Mathematics|Manual correction>:
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<\description>
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<item*|<menu|Remove superfluous invisible operators>>This algorithm is
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used in order to remove any superfluous function applications or
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multiplications. For instance, users who are accustomed to editing ASCII
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files often type spaces around binary infixes such as addition. Such
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\Pfunction applications\Q will be removed by this algorithm.
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<item*|<menu|Insert missing invisible operators>>In <LaTeX>,
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multiplications and function applications are never entered explicitly.
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When importing a <LaTeX> document, it is therefore important to detect
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and insert missing multiplications and function applications.
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<item*|<menu|Homoglyph substitutions>>This algorithm may perform some
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other useful substitutions of symbols by visually similar, but
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semantically distinct symbols. For instance, the backslash
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symbol<nbsp><math|\\> is replaced by the binary set differences infix (as
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in <math|X\<setminus\>Y>), whenever appropriate.
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</description>
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From the <menu|Edit|Preferences|Mathematics|Automatic correction>, you may
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also select those corrections algorithms which should be applied
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automatically whenever you open a file. The various corrections are always
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carried out when importing a <LaTeX> file.
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After syntax correction, the remaining errors indicate genuine typos at
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worst or non standard or non supported notations at best. We also notice
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that \Pcorrect\Q formulas do not necessarily have the intended meaning. In
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order to check whether the operators indeed apply to the intended
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arguments, you should keep an eye on the current focus while typing your
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formulas.\
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<tmdoc-copyright|2010|Joris van der Hoeven>
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<tmdoc-license|Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation; with no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled "GNU Free
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Documentation License".>
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</body>
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<initial|<\collection>
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</collection>> |