Alexander Bolotov Artie Basukoski Oleg Grigoriev Vasilyi Shangin Natural Deduction Calculus for Linear-Time Temporal Logic. 56-68 2006 conf/jelia/2006 JELIA http://dx.doi.org/10.1007/11853886_7 db/conf/jelia/jelia2006.html#BolotovBGS06