% Specification of the railroad crossing example from M. Kanovich, M. Okada,
% and A. Scedrov, "Specifying Real-Time Finite-State Systems in Linear Logic".
% Forward chaining with variables.
% Date: 7 July  1998
% Author: Iliano Cervesato

Forward chaining with variables:

+ direct transcription of the specifications
+ final values are available

+ not as efficient as plain forward chaining (44 GC in the example)


Performance (measured in number of calls to the GC)
* success (1,2,3,4) : 45 (avg)
* failure (1,1,1,4) : 8 (avg)