The hm Package

The hm package is an open-source Common Lisp package for investigating the chronological structure of archaeological stratigraphy.

With hm you can:

• represent the Harris matrix as a stratigraphic acyclic directed graph (DAG) as described by Dye and Buck (2015)
• investigate and analyze the structure of the Harris matrix using graph theoretic functions and characteristics of the archaeological data
• generate a chronological DAG that can guide data input for Bayesian calibration software such as BCal, OxCal, or Chronomodel
• create a graphic visualization of a stratigraphic DAG or a chronological DAG in any one of the graphics formats supported by the open-source Graphviz dot software

A central organizing principle of the hm software is the self-contained project. An hm project has its own file directory that includes:

• two or more input files with information on
  • units of archaeological stratification, or contexts
  • observations of stratigraphic superposition
  • inferences of once-whole contexts
  • periods
  • phases
  • dated events
  • event order
• one or more initialization files that specify
  • input files
  • classifiers that are mathematical functions on the stratigraphic DAG or archaeological constructs specified by the excavator
  • output files
  • parameters to configure the Graphviz dot software
• zero or more output files generated during investigation and analysis

The hm software is designed to be collaborative:

• input files are comma-separated value text files that can be produced by
  • most spreadsheet applications
  • most database software
  • any text editor
• initialization files are the widely-used .ini file format
• the text file output from hm is processed by the Graphviz dot software
• compressed hm project archives can be sent via email to colleagues, who will then have the information needed to replicate a stratigraphic investigation and analysis
• planning is underway to design an interface from hm to Bayesian calibration software