MLT – Multi-Level Theory

This is a resources page for the MLT Multi-Level Theory. MLT formally characterizes the nature of classification levels, and precisely defines the relations that may occur between elements of different classification levels, generalizing the notion of power type.

Original paper describing MLT: carvalho-almeida-sosym-final revision (published at ttp://

Paper describing MLT*, a generalization of MLT to account for broader multi-level phenomena a_comprehensive_formal_theory_for_multi_level_conceptual_modelling

MLT Repository on Github with formal specification in Alloy:

MLT Repository on Github with OWL ontology reflecting MLT rules:

M.Sc. thesis describing the ML2 language based on MLT*: ml2-dissertation

ML2 presentation (slides used in Dagstuhl seminar on Multi-Level Modeling): ml2-presentation