lib/logo/index.html
 author Lars Hupel Thu, 06 Mar 2014 17:55:39 +0100 changeset 55946 5163ed3a38f5 parent 33686 8e33ca8832b1 permissions -rw-r--r--
tuned
```
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>The Isabelle Logo</title>

<body>

<h1>The Isabelle Logo</h1>

<h2>Versions</h2>

The logo is available as bitmap file for the generic Isabelle system
(<a href="#plain">plain</a>, <a href="#transparent">transparent</a>)
and major object logics (<a href="#ZF">ZF</a>, <a href="#HOL">HOL</a>,
<a href="#HOLCF">HOLCF</a>).  There are also <a
href="isabelle-small.xpm">small</a> and <a
href="isabelle-tiny.xpm">tiny</a> Isabelle icons available.
Furthermore, scalable (EPS) versions of the logo may be generated for
any logic using the <tt>isabelle logo</tt> utility distributed with
Isabelle.

<h2>Interpretation</h2>

<img src="isabelle.gif" align=right alt="[Isabelle logo]"> First of
all, the logo tells about the name of the generic system, Isabelle, or
of its concrete instantiations, e.g. Isabelle/HOL.  It also expresses
some essentials of the overall Isabelle design philosophy: Composition
of several small well understood building blocks, grouped together or
arranged in layers. <p>

The markings on the cubes illustrate this general principle by example
of the core meta-logic (which is minimal higher-order logic on top of
naively polymorphic simply typed lambda calculus). Thus red cubes
symbolize the type system with function spaces (-&gt;) and type
variables (alpha); violet ones represent the lambda term language with
beta conversion etc.; yellow cubes constitute the actual logical
parts, namely meta-implication or entailment (|-) and meta-level
universal quantification.

<h2>Acknowledgment</h2>

The logo is contributed by <a
href="http://www.informatik.tu-muenchen.de/~wenzel/">Franziska
Wenzel</a>, Munich.  It has been designed on Apple Macintosh.

<p><hr><p>

<a name="plain"><img src="isabelle.gif" alt="[Isabelle logo]"></a> <p>

<a name="transparent"><img src="isabelle_transparent.gif" alt="[Isabelle logo (transparent)]"></a> Note: This may look bad on
black and white displays. <p>

<a name="ZF"><img src="isabelle_zf.gif" alt="[Isabelle logo (ZF)]"></a> <p>

<a name="HOL"><img src="isabelle_hol.gif" alt="[Isabelle logo (HOL)]"></a> <p>

<a name="HOLCF"><img src="isabelle_holcf.gif" alt="[Isabelle logo (HOLCF)]"></a>

</body>
</html>
```