modif singularities

Manuscript/EPAWTFT.tex

@@ -196,7 +196,8 @@ We refer the interested reader to the excellent book of Moiseyev for a general o
 At a singular point, a function and/or its derivatives becomes infinite or undefined (hence non analytic).
 One very common type of singularities (belonging to the family of isolated singularities) are poles where the function behaves $1/(\lambda - \lambda_c)^n$ where $n \in \mathbb{N}^*$ is the order of the pole.
 Another class of singularities are branch points resulting from a multi-valued function such as a square root or a logarithm function and usually implying the presence of so-called branch cuts which are lines or curves where the function ``jumps'' from one value to another.
-Yet another family of singularities are formed by critical points which lie on the real axis, have more complicated functional forms and where the nature of the function undergoes a sudden transition.
+Critical points are singularities which lie on the real axis and where the nature of the function undergoes a sudden transition. 
+However, these do not clearly belong to a given class of singularities and they cannot be rigorously classified as they have more complicated functional forms.
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