The Isabelle Logo
Versions
The logo is available for the generic Isabelle system (plain, transparent) and
major object logics (ZF, HOL, HOLCF). There are also small and tiny Isabelle icons available.
Furthermore, there are EPS versions of the plain and the HOL Isabelle logo.
Interpretation
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.
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 (->) 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.
Acknowledgment
The logo is contributed by Franziska
Wenzel, Munich. It has been designed on Apple Macintosh.
Note: This may look bad on
black and white displays.