Why doesn't mathematica evaluate this?

*To*: mathgroup at smc.vnet.net*Subject*: [mg119818] Why doesn't mathematica evaluate this?*From*: Jacare Omoplata <walkeystalkey at gmail.com>*Date*: Fri, 24 Jun 2011 07:44:44 -0400 (EDT)

Here's the output. Out[102] lists the assumptions I've used. It doesn't evaluate out[104], but the inequality from Out[104] can be arrived at by the inequalities In[105] and In[106], each of which evaluate to true by themselves. If the L.H.S. of In[105] is multiplied by the L.H.S. In[106], and the R.H.S. of In[105] is multiplied by the R.H.S. of In[106], then the inequality at Out[104] can be arrived at. Is there a workaround? ------------------------------------- output---------------------------------------------- In[102]:= $Assumptions Out[102]= {(x1 | x2 | t1 | t2 | u | c) \[Element] Reals, u < c, t1 < t2, u > 0, x2 > x1, c t1 + x2 < c t2 + x1} In[103]:= dT Out[103]= -((t1 - (u x1)/c^2)/Sqrt[1 - u^2/c^2]) + ( t2 - (u x2)/c^2)/ Sqrt[1 - u^2/c^2] In[104]:= FullSimplify[dT > 0] Out[104]= c^2 t2 + u x1 > c^2 t1 + u x2 In[105]:= FullSimplify[(u/c) < 1] Out[105]= True In[106]:= FullSimplify[((x2 - x1)/(c*(t2 - t1))) < 1] Out[106]= True