pattern-observers

This repository captures the derived Lustre and Simulink Design Verifier (SLDV) synchronous observers for the specification patterns work at http://patterns.projects.cis.ksu.edu/

This work only supports a subset of the patterns defined on the Specification Patterns website.

The supported scopes from the original work are:

• global
• before p
• after p
• after p until q
• between p and q
• while p (introduced in this work, it is a simplification of after p until not p)

The supported predicates from the original work are:

• always a
• exists a
• a precedes b
• a responds to b

Any combination of scope and predicate can be used to create a pattern. Some combinations of scope and predicate express liveness conditions and accordingly cannot be verified using k-inductive tools (such as Kind or SLDV). These combinations are:

• global :: exists a
• global :: a responds to b
• after p :: exists a
• after p :: a responds to b
• after p until q :: exists a
• after p until q :: a responds to b
• while p :: exists a
• while p :: a responds to b

In this case we bound the time in which we expect the satisfying event to occur. For example

global :: a responds to b becomes global :: a responds to b within N

Where N represents the number of computation steps we expect b to occur within.