We analyze the fundamental solution of a time-fractional problem, establishing existence and uniqueness in an appropriate functional space.
We also focus on the one-dimensional spatial setting in the case in which the time-fractional exponent is equal to, or larger than, $ \frac12 $. In this situation, we prove that the speed of invasion of the fundamental solution is at least "almost of square root type", namely it is larger than $ ct^\beta $ for any given $ c>0 $ and $ \beta\in\left(0,\frac12\right) $.
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