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6 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
7 <title>The Isabelle Logo</title>
12 <h1>The Isabelle Logo</h1>
16 The logo is available as bitmap file for the generic Isabelle system
17 (<a href="#plain">plain</a>, <a href="#transparent">transparent</a>)
18 and major object logics (<a href="#ZF">ZF</a>, <a href="#HOL">HOL</a>,
19 <a href="#HOLCF">HOLCF</a>). There are also <a
20 href="isabelle-small.xpm">small</a> and <a
21 href="isabelle-tiny.xpm">tiny</a> Isabelle icons available.
22 Furthermore, scalable (EPS) versions of the logo may be generated for
23 any logic using the <tt>isabelle logo</tt> utility distributed with
27 <h2>Interpretation</h2>
29 <img src="isabelle.gif" align=right alt="[Isabelle logo]"> First of
30 all, the logo tells about the name of the generic system, Isabelle, or
31 of its concrete instantiations, e.g. Isabelle/HOL. It also expresses
32 some essentials of the overall Isabelle design philosophy: Composition
33 of several small well understood building blocks, grouped together or
34 arranged in layers. <p>
36 The markings on the cubes illustrate this general principle by example
37 of the core meta-logic (which is minimal higher-order logic on top of
38 naively polymorphic simply typed lambda calculus). Thus red cubes
39 symbolize the type system with function spaces (->) and type
40 variables (alpha); violet ones represent the lambda term language with
41 beta conversion etc.; yellow cubes constitute the actual logical
42 parts, namely meta-implication or entailment (|-) and meta-level
43 universal quantification.
46 <h2>Acknowledgment</h2>
48 The logo is contributed by <a
49 href="http://www.informatik.tu-muenchen.de/~wenzel/">Franziska
50 Wenzel</a>, Munich. It has been designed on Apple Macintosh.
55 <a name="plain"><img src="isabelle.gif" alt="[Isabelle logo]"></a> <p>
57 <a name="transparent"><img src="isabelle_transparent.gif" alt="[Isabelle logo (transparent)]"></a> Note: This may look bad on
58 black and white displays. <p>
60 <a name="ZF"><img src="isabelle_zf.gif" alt="[Isabelle logo (ZF)]"></a> <p>
62 <a name="HOL"><img src="isabelle_hol.gif" alt="[Isabelle logo (HOL)]"></a> <p>
64 <a name="HOLCF"><img src="isabelle_holcf.gif" alt="[Isabelle logo (HOLCF)]"></a>