SpecForge Introduces Lilo Language for Formal Specification of Hybrid Systems

Introduction to Lilo Language

SpecForge has introduced Lilo, an expression-based temporal specification language. Lilo is specifically designed for authoring formal specifications for hybrid systems, which involve both continuous and discrete dynamics. The language is integrated with a VSCode extension for analysis.

Key Features of Lilo

Lilo supports primitive data types such as Bool, Int, Float, and String, along with standard arithmetic, comparison, and logical operators. A distinguishing feature of Lilo is its rich set of temporal logic operators, including 'always', 'eventually', 'past', and 'historically'. These operators can be qualified with time intervals, allowing for precise temporal constraints.

System Organization in Lilo

Lilo specifications are structured into 'systems'. Each system groups together various declarations: 'signals' for time-varying input values, 'params' for non-temporal parameters, 'types' for custom data structures, and 'definitions' for reusable functions. The 'specifications' within a system define the requirements that the system must satisfy.

Practical Application Example

An example project, a temperature control system, demonstrates Lilo's capabilities. This system monitors temperature and humidity sensors, with specifications ensuring that sensor values remain within predefined safe ranges. For instance, specifications can define that temperature must always be within a minimum and maximum range, or that humidity correlates with temperature within certain conditions.