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What is Tactician?

Tactician is a tool for helping you maintain and/or understand HOL Light proof scripts. Its main function is to refactor the ML of a tactic proof, typically to package up a "g/e" style proof into a "prove" style proof, or vice versa, to flatten out a "prove" style proof into a series of "g/e" style interactive steps. This can help experienced users maintain their proof scripts, and novices learn from existing proof scripts.

Once loaded into a HOL Light session, it runs in the background, dynamically capturing tactic proofs as they are executed, and outputting upon user request. It is capable of refactoring tactic proofs written in the following styles:

Tactician also supports various other related activities, such as visualising the tree of subgoals of a tactic proof, spotting slow tactic applications and duplicate theorems, and viewing the dependencies between theorems. These facilities are particularly useful when managing large proof rojects.

See here for some simple examples of its refactoring capability. We have also written a paper giving an overview of Tactician and its implementation.

Download and Installation

A source tarball for the latest version can be downloaded here:

hollight_tactician-3.1.tgz (released 2015-01-10).

Unpack the downloaded tarball as a subdirectory of your existing HOL Light installation directory, by executing the following command from a terminal window, to result in a directory called Tactician:

tar -xzf hollight_tactician-3.1.tgz -C your-hollight-dir

Users are encouraged to rebuild OCaml specially for Tactician usage. Doing this avoids the need to execute promote_all_values before each proof you want to refactor (see below). See the Tactician release README for full details on how to rebuild.

Tactician can be loaded into an existing HOL Light session in about 5 to 30 seconds (depending on your system hardware and how many theorems have already been proved in the session) by executing the following ML directive in the HOL Light session (where the first # indicates the OCaml prompt):

# #use "Tactician/";;

Tactician is then ready to record and refactor proofs in terms of the ML bindings referred to in the original proof script. For a full description of Tactician's capabilities, see USER_GUIDE bundled with the Tactician release.