  Metric Temporal Logic (MTL) and Timed Propositional Temporal Logic (TPTL) are
prominent real-time extensions of Linear Temporal Logic (LTL). In general, the
satisfiability checking problem for these extensions is undecidable when both
the future U and the past S modalities are used. In a classical result, the
satisfiability checking for MITL[U,S], a non punctual fragment of MTL[U,S], is
shown to be decidable with EXPSPACE complete complexity. Given that this notion
of non punctuality does not recover decidability in the case of TPTL[U,S], we
propose a generalization of non punctuality called \emph{non adjacency} for
TPTL[U,S], and focus on its 1-variable fragment, 1-TPTL[U,S]. While non
adjacent 1-TPTL[U,S] appears to be be a very small fragment, it is strictly
more expressive than MITL. As our main result, we show that the satisfiability
checking problem for non adjacent 1-TPTL[U,S] is decidable with EXPSPACE
complete complexity.
