techexplorer

IBM techexplorer displays documents containing scientific and mathematical expressions that are coded with a subset of the popular T_EX, L^AT_EX and MathML markup languages.

This document is available on the web at http://centaur.maths.qmw.ac.uk/CTI_MathML_Workshop/, which contains many links to further information. Please use the online version for the hands-on practical session.

Introduction

What is techexplorer?

The IBM techexplorer Hypermedia Browser is a plug-in for Netscape Navigator and Microsoft Internet Explorer, enabling the display of T_EX, L^AT_EX and MathML documents and the publishing of interactive mathematical and scientific material on the Web. It dynamically formats and displays large subsets of T_EX and L^AT_EX, including AMS-L^AT_EX. Version 2.5 supports the complete MathML Content Tag Set and a substantial subset of the MathML Presentation Tag Set.

Full information and downloading is available from http://www.software.ibm.com/network/techexplorer/. techexplorer runs on Microsoft Windows 95/98/NT and some versions of UNIX (AIX, Linux, SGI IRIX, Sun Solaris).

I will describe only Version 2.5 of the no-charge (but licensed) Introductory Edition. There is also a commercially available Professional Edition. Much of this document is based on the online documentation included with techexplorer.

techexplorer's heritage

techexplorer is being developed by the Interactive Scientific Publishing Group at IBM Research. The manager, Robert Sutor, was a key member of the IBM Research Group who developed the Scratchpad computer algebra system, which has been marketed by NAG as Axiom since about 1990.

What is a plug-in?

There are currently three ways to extend the capabilities of a web browser: plug-ins, applets and scripts, and helper applications.

Plug-ins are software programs that extend the capabilities of a web browser to handle one or more data (MIME, see below) types. They are separate code modules written in C/C++ and distributed as compiled machine code, which is therefore platform specific. They were introduced by Netscape in Navigator 2.0 in the first quarter of 1996.

A plug-in must be explicitly installed on a computer. It is then automatically started by the web browser when it encounters a document with the MIME type registered for that plug-in, and run within the browser almost as if it were a core part of the browser. Not all browsers support plug-ins, and they tend to work best in Netscape Navigator. (See the Netscape Communicator web-based documentation for details.)

Plug-ins versus Java applets and JavaScript etc.

Java applets, JavaScript (being standardized by the European Computer Manufacturers Association as the ECMAScript Language Specification) and other scripting languages provide other ways of extending browser capabilities. (Despite their names, Java and JavaScript are not closely related.) The code is supposed to be platform independent and does not need to be explicitly installed, so is a little more transparent than a plug-in. Java is normally downloaded automatically from a server as necessary and JavaScript is normally embedded in an HTML source document. Java is normally compiled to an intermediate language (but not machine code) before being interpreted by the Java Virtual Machine built into the browser and JavaScript is interpreted directly, so a machine-code plug-in should execute faster. Java is mainly used for applications such as animated graphics, but can also be used to render mathematics (e.g. WebEQ, IDVI). JavaScript is mainly used for additional browser control, e.g. to improve the user interface and handle some aspects of forms, and could not be used to render mathematics.

Plug-ins versus Helper Applications

A helper application is a separate, free-standing application that can be started from the browser. A document is passed to a helper application via a temporary file or pipe.

Like a plug-in, the browser starts a helper application when the browser encounters a MIME type that is mapped to it. Unlike a plug-in, a helper application runs separately from the browser in its own application space and does not interact with the browser or the web.

When Navigator encounters a MIME type, it always searches for a registered plug-in first. If there are no matches for the MIME type, it looks for a helper application.

Plug-ins and helper applications fill different application needs. Under Windows, helper applications should be installed automatically, but the mechanism seems to be a little unstable and depends critically on somewhat inscrutable registry entries!

Maple Explorer

Maple Explorer is a version of techexplorer tailored for use with Maple V Release 5.1. However, Adept Scientific tell me that this has been withdrawn, due to some disagreement between IBM and Waterloo Maple. It is still possible to use the standard techexplorer with Maple (see below), but only in a much more limited way.

I thank Adept Scientific for providing me with information about Maple Explorer and an evaluation copy of Maple V Release 5.1.

Amaya

Amaya is W3C's own reference browser/authoring tool and is used to demonstrate and test many of the new developments in Web protocols and data formats. It is freely available as source or (for some platforms) binary code. It supports many features not supported by other free browsers or editors, but beware that it feels a little rough to use!

Background and context

Displaying Maths

Non-proprietary formats that support complete documents, including maths

Proprietary formats that support complete documents, including maths

Display processors for the above formats

MIME types

The MIME (Multipurpose Internet Mail Extensions) type specifies the format of a document. (It was originally designed to extend the format of Internet mail to allow non-US-ASCII textual messages, non-textual messages, multipart message bodies, and non-US-ASCII information in message headers.)

The MIME type is either determined and sent by the web server for a remote document, or determined by the web browser for a local document, based on the filename extension. This information is configurable. Browser plug-ins, such as techexplorer, normally register a set of MIME types and corresponding filename extensions to which they will respond. A dynamically generated document (e.g. a response to a form) can specify any MIME type desired by the programmer. For example, this might allow the user to select either ASCII or T_EX output from a remote computer-algebra computation (as for my CATHODE demos).

Generating Maths for the Web

Static documents

My current recommended format for static documents is PDF to be viewed using Adobe Acrobat Reader.

Dynamic documents

These can be generated using any convenient program(s). A standard and portable technology is CGI (Common Gateway Interface), which allows information to be passed from an HTML form on a web browser via a server to any program, and the output from the program to be passed back to the browser, to either a new page or an existing frame (in principle).

A perl script is commonly used as the principle CGI processor. It might generate mathematical output directly or, more likely, indirectly by calling a computer algebra system. (For further details see the WebDemo talk I gave at the last CATHODE Workshop; both the presentation and extended abstract are available. Incidentally, these are respectively Microsoft Word and L^AT_EX documents converted to PDF.)

My current recommended formats for dynamic documents are (L^A)T_EX or HTML with embedded MathML to be viewed using IBM techexplorer.

REDUCE 3.7

REDUCE is probably the oldest computer algebra system still in wide use. It predates MACSYMA by a couple of years and Maple by a decade! REDUCE 3.7 was formally released on April 30th, 1999. One of the new facilities is an interface between REDUCE and MathML. There are currently distributed implementations of REDUCE based on two different Lisp systems: ZIB (Konrad-Zuse-Zentrum für Informationstechnik Berlin) offers a version based on PSL and Codemist (Cambridge/Bath, UK) offers a version based on CSL. CSL (Codemist Standard Lisp) is written in C.

The Windows and X graphical user interfaces offered by PSL-REDUCE use T_EX as an intermediate language for typeset mathematical display, and any implementation can generate output in T_EX format by using the standard alternative print module fmprint. The result requires trivial post-processing to be acceptable to techexplorer or another T_EX processor. This technique is used in my CATHODE REDUCE demos. I plan to add an option to generate MathML instead of T_EX using a similar technique. REDUCE provides two other packages (RLFI and TRI) for generating T_EX output with more user control.

Maple V Release 5.1

Maple dates back to about 1980, and Maple V Release 5.1 is the current version. One of the new facilities is that Maple worksheets on the Internet may be accessed directly via a URL, as an alternative to using Maple as a helper application. This makes them a viable (but proprietary) format for mathematics on the web. (Demonstration: copy this link and paste it into the Maple URL box).

The "Export As HTML" or "Export As LaTeX" options provide portable alternatives. Release 5.1 also provides an option to "Export As Maple Explorer", but the result appears to be the same as "Export As LaTeX". The result requires a special L^AT_EX style file called "maple2e", which cannot be processed by techexplorer. Hence, techexplorer displays a lot of uninterpreted commands that would need to be removed by postprocessing. Maple also provides a "latex" command for outputting specific results in L^AT_EX, but currently there appears to be no support for MathML.

(L^A)T_EX versus HTML/MathML

Advantages of (L^A)T_EX documents

Advantages of HTML/MathML documents

Using techexplorer

These notes are based on the chapter entitled "Creating techexplorer Documents" in the online documentation, which is accessible (using Windows) via the Start menu option "Programs/IBM techexplorer HyperMedia Browser/Documentation".

Style and class files

It is very important to note that techexplorer is not "real T_EX" and in particular does not read L^AT_EX style (or class) files.

Invoking techexplorer

For a complete document to be rendered using techexplorer it must have one of the following MIME types (if remote) or filename extensions (if local):

MIME type	Corresponding File Extensions
`application/x-tex`	`.tex, .bbl`
`application/x-latex`	`.latex, .ltx`
`application/x-techexplorer`	`*.tcx`
`text/mathml`	`*.mml`

For part of a document to be rendered using techexplorer it must be specified using the HTML <embed> tag. (This is the current de facto standard tag for including executable document content whose MIME type references the plug-in needed to process it. However, the official HTML 4.0 standard tag for this purpose is <object> -- see [HTML: The Definitive Guide by Chuck Musciano & Bill Kennedy, O'Reilly, 3rd Edition, 1998].) The tag attributes include either a file of one of the above types or the actual markup. The more elegant MathML <math> tag works only if it is supported by the native browser, in which case it would be expected to render the mathematics directly anyway.

In practice, this means that at present non-trivial mathematical content is best handled by techexplorer as a single (L^A)T_EX file rather than by trying to embed T_EX or MathML markup in some other document type.

techexplorer extensions and restrictions

This section summarizes some of the extensions to (L^A)T_EX that techexplorer provides to support interactive document browsing. Other extensions and restrictions are described in the techexplorer online documentation.

Hypertext Links

These are provided by techexplorer extensions to (L^A)T_EX. Use \docLink to jump to another network document and \labelLink to jump to another location within the same document. The standard \label and \index commands have the non-standard side-effect of defining targets for hypertext links. The \aboveTopic, \nextTopic and \previousTopic commands can be used to define a document hierarchy, as used for example in Windows help documents and GNU TeXinfo documents. techexplorer does not currently handle automatic numbering.

Graphics

Other link types

Including MathML within a L^AT_EX file

This is currently possible only in Windows, using either \includeMathML{mmlFileName} or \begin{MathML} ... \end{MathML}.

Pop-up menus

Hands-on practical session

Here are some suggestions. Follow any of the links above that may be of interest to you for further background information. Note that all the software provided to support this session is freely available except for Maple, so if you do not normally have access to Maple you may prefer to focus on trying it now!

Look at the techexplorer introductory edition examples

These should be accessible (using Windows) via the Start menu option "Programs/IBM techexplorer HyperMedia Browser/Examples". Temporarily, you can also access them locally via this link: Examples. (The online documentation is also temporarily available via this link: Documentation.)

A few points are worth noting. The extension of each file browsed indicates its type, which in this case will be either .html or .tex. In the former case (.html), techexplorer is rendering only specific regions of the document, whereas in the latter (.tex) it is rendering all of it. One way to see the difference is to right-click the mouse. The context menu that appears is different depending on whether the browser or techexplorer is rendering the document at the point where the mouse was clicked. The source code of a page being browsed should be accessible via a menu even if the page is being rendered by a plug-in, and shows exactly how the page has been constructed.

The MathML Content markup examples are a slight cheat, because they are .tex files that are neither strict T_EX nor strict HTML/MathML, but are instead MathML embedded in a L^AT_EX document using commands specific to techexplorer.

The MathML Presentation markup examples are .html files that embed .mml source files. While browsing one of these files, it is an interesting experiment to change the .html to .mml in the browser's URL (Address or Location) field (and press Return), which will cause the browser to load the MathML (.mml) file directly. At present a plug-in can access MathML only as a separate file either directly or embedded in an HTML document: the more elegant <math> tag to incorporate MathML requires native browser support that is provided by Amaya but not by most other browsers.

The CATHODE demonstrations

CATHODE is an ESPRIT Working Group concerned with the development of computer algebra tools for handling differential equations. For purposes of software demonstration required by the project, I have developed web-based form interfaces to four packages written by UK CATHODE members. The demonstrations all provide prettyprinted ASCII output by default with an option to generate T_EX output for use with techexplorer as an alternative. Hence, you can compare these two alternatives in the context of dynamically generated solutions of differential equations. Three of the demonstrations use REDUCE and run on two servers: the advertised server "cathode.maths.qmw.ac.uk" and my development server "centaur.maths.qmw.ac.uk". One of the demonstrations uses Maple and runs only on centaur. The demonstrations all include some "canned examples", which can be used to generate some mathematical output regardless of whether you completely understand the problem being solved! They also all provide the facility to enter your own problems. Please do not try to solve difficult problems that will use excessive resources on the servers and prevent other users from accessing them! Beware that the demonstrations are still under development, and in particular the options to use frames do not yet work reliably. I suggest you take a quick look through any of the demonstrations that appeal to you and then try a few of the simpler canned examples, first without and then with the T_EX output selected.

I recommend starting with the ODESolve demonstration, which is a simple REDUCE solver for single ODEs. (For further details see the ODESolve talk I gave at the last CATHODE Workshop; both the presentation and extended abstract are available. Incidentally, these are respectively Microsoft Word and L^AT_EX documents converted to PDF, which contain a small amount of mathematics. If you have techexplorer installed then you can also browse a longer paper describing the development of an earlier version of ODESolve.)

The diffgrob2 demonstration provides an example of the use of Maple. The canned examples in the table of diffgrob2 facilities all run quickly, although other examples can be very slow. However, note that this particular demonstration cheats slightly, because the standard diffgrob2 output format uses T_EX syntax so it is not generated by Maple. (In fact, in order to offer prettyprinted ASCII output in this demonstration I had to modify the diffgrob2 source code very slightly.) However, for a demonstration of different Maple-based software, I could have generated T_EX output using standard Maple facilities as I have with REDUCE.

You are welcome also to try the CRACK and ConLaw demos. These package are very powerful but consequently harder to understand. (I only claim to understand ODESolve!)

If you are interested in the detailed operation of the demos then the package source code is all freely available via the demo pages, and my perl CGI scripts (which provide the glue between the web server and the CAS) are (temporarily) available in the directory http://centaur.maths.qmw.ac.uk/CATHODE/CGI/.

Case study: a computational mathematics examination paper

The QMW courses Computational Mathematics I and II are intended to teach our first-year undergraduate mathematics students how to perform computational mathematics using Maple. I teach CMII, and I use Maple to prepare the examination paper (and most of the other course documentation). The process of producing this exam paper provides a natural source for comparing various formats for putting mathematics on the web.You can look at many of the files directly, and/or download a file and explore some of the same steps yourself. The files described below are all available in the directory Exam; it is interesting to clink on this link to display a directory listing and compare the file sizes. The steps I take and the formats involved are as follows:

You can (in principle) access these files directly via the web, or first download them to local filestore.

If Maple V Release 5.1 is available then you can open the .mws files directly by copying the URLs from this document into the "Open URL" dialogue available via a toolbar button or the File menu. If only an earlier release of Maple is available then you will need to use a web browser to download the files before you can open them. They are Release 5 worksheets; Release 4 may complain but will probably open them, although they may need re-executing to reconstruct all the output; earlier releases will not work. Try exporting the worksheet as various formats.

If techexplorer is installed (which it is for the workshop) then you can open the L^AT_EX file directly. However, it will not read the document class file and so will not understand some of the macros used. (Exactly the same effect would occur with the L^AT_EX file exported directly from Maple, except that it is the Maple style file that would not be read.) Uninterpreted T_EX commands are shown by techexplorer in red (by default). To see exactly what the L^AT_EX source code looks like, clink on this link Exam99.txt (which is just a copy of Exam99.tex with a different filename extension) or select the browser option to view the source (which may not be useful in all broswers).

You may like to try downloading Exam99.tex and then editing it to remove some or all of the commands that techexplorer does not understand, perhaps replacing them with standard commands. Alternatively, you may like to just browse the file Exam99.latex in which I have already done precisely this, so that it renders well in techexplorer (but does not have quite the right format). To see how the exam paper should appear look at one of the files Exam99.pdf, Exam99.dvi or Exam99.ps. (Given the incentive, it should not be hard to incorporate the exam class file into the document in such a way that techexplorer would render it more accurately and without needing any editing.)

If L^AT_EX2e is available then you can try formatting the source file. To do this, download both Exam99.tex and exam.cls to the same directory on your local machine, open a command window in that directory and execute the command "latex exam99". (Windows programs are not normally case sensitive.) You can view the DVI file via the web by using a previewer (such as Yap, which is part of MiKTeX, the T_EX distribution that I recommended for Windows) as a web browser helper application, or by downloading it.

You can view the PostScript file either via the web by using a PostScript viewer, such as GSView for Windows, as a helper application, or by downloading it. You can view the PDF file either via the web by installing the Adobe Acrobat Viewer plug-in, or by downloading it.

Finally, you can view the HTML file via the web just by clicking on the link above; there is little advantage in downloading this and the big disadvantage that it requires the support of a large number of small GIF files.

Write and view some of your own (L^A)T_EX code

In Windows, Notepad is a rudimentary editor that should be available under Programs/Accessories in the Start menu and will suffice for writing small code fragments. Some online L^AT_EX help may be available, e.g. under Programs/MiKTeX/Help. To view the T_EX file using techexplorer, it is not necessary to use a web server; just open the T_EX file using a web browser. One simple way to do this is to drag the file from Windows Explorer onto a browser icon, either on the desktop or on the Quick Launch toolbar on the taskbar (depending on how Windows is set up). Note that techexplorer does not require a complete L^AT_EX document structure; provided the mathematical input is enclosed in a suitable (L^A)T_EX environment then techexplorer will render it. For example, if you copy this single line of L^AT_EX into a file with a suitable extension (such as .tex) and then drag it onto a browser, techexplorer should render it as displayed mathematics

(To check this assertion, I did precisely this to produce the file test.tex. I actually generated this example using Maple, as described in the next section!)

Use Maple to generate (L^A)T_EX code

I have created a very simple Maple worksheet called Example_1.mws to illustrate various ways of using Maple to generate (L^A)T_EX that is suitable for displaying using techexplorer. Obvious advantages of this approach are that it is not necessary to be familiar with (L^A)T_EX, and any mathematical computation required can be done by Maple before the (L^A)T_EX is generated.

Convert T_EX to MathML

TtHMML is Ian Hutchinson's powerful (L^A)T_EX to HTML/MathML translator (and the comments on the TtHMML page are interesting). TtHMML is still in development, but a web-based demonstration is available. It is therefore possible to take a short segment of (L^A)T_EX and render it using techexplorer, and also to convert it to HTML/MathML and render that, and compare the results. However, currently the only browser that will render the MathML is Amaya, but Amaya does not appear to support techexplorer. (In fact, it is not clear that Amaya supports plug-ins at all.) So you probably need to use two different browsers for this experiment!

Try Amaya

If the Amaya browser/editor is available then you might like to try using it to view some existing MathML files, such as those provided as techexplorer examples, and comparing the result with those of techexplorer. You might also like to try using it to create some MathML yourself. The documentation claims that this is easy. But beware: my experience is that this is not true unless you are already very familiar with both Amaya and MathML!

Beware also that it seems that Amaya currently hangs when it tries to open a file of any type other than HTML, which unfortunately includes both .tex and .mml files! To browse .mml files using Amaya, try wrapping the MathML in <math> </math> tags and changing the file extension to .html. The file mml002.html is a minimally edited techexplorer example file that I used to ensure that this advice works!

Bibliography

A Gentle Introduction to MathML (HTML version), (PostScript version) - By Robert Miner and Jeff Schaeffer.
(The PostScript version is also temporarily available locally.)

MathML: Putting Mathematical Notation on the Web CTI Workshop, Electronic Engineering, QMW, 25th June 1999

IBM techexplorer: introduction and hands-on practical session

Abstract

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