<pstyle="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">un <spanstyle="color:#0066cc"> invariant temporel<br>
<spanstyle="font-family:'Times New Roman';margin-left:30px;font-weight:bold;font-size:0.85rem;text-align:right;color:#6699ff">entre deux instants t<sub>1</sub> et t<sub>2</sub> du temps</span><br>
<spanstyle="font-family:'Times New Roman';margin-left:30px;font-weight:bold;font-size:0.85rem;text-align:right;color:#6699cc">entre deux instants t<sub>1</sub> et t<sub>2</sub> du temps</span><br>
<spanstyle="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;color:#bbbbbb">appelé
</span><spanstyle="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;left;color:#bb3300"> durée Δt<sub>1 2</sub></sub></span><br>
<spanstyle="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">d'expression</span></p>