diff --git a/dissertation/dissertation.pdf b/dissertation/dissertation.pdf index 9a688fe..a9185f2 100644 Binary files a/dissertation/dissertation.pdf and b/dissertation/dissertation.pdf differ diff --git a/dissertation/dissertation.tex b/dissertation/dissertation.tex index acf264a..76a80ab 100644 --- a/dissertation/dissertation.tex +++ b/dissertation/dissertation.tex @@ -610,21 +610,69 @@ persistence diagrams and Banach spaces. \section{Vectorization methods}% \label{sec:vect-meth} +%% TODO + \subsection{Persistence landscapes} +Persistence landscapes~\cite{bubenik_statistical_2015} are a mean to +project the barcodes in a space where it will be possible to add them +meaningfully. It would thus be possible to define means of persistence +diagrams, along other summary statistics. + +As all the other vectorization techniques mentioned here, this +approach is \emph{injective}, but not surjective, and no explicit +inverse exists to go back from a persistence landscape to the +corresponding persistence diagram. Moreover, a mean of persistence +landscapes do not necessarily have a corresponding persistence +diagram. + +\begin{defn}[Persistence landscape] + The persistence landscape of a diagram $D = \{(b_i,d_i)\}_{i=1}^n$ + is the set of functions $\lambda_k: \mathbb{R} \mapsto \mathbb{R}$, + for $k\in\mathbb{N}$ such that + \[ \lambda_k(x) = k\text{-th largest value of } \{f_{(b_i, + d_i)}(x)\}_{i=1}^n, \] (or zero if the $k$-th largest value does + not exist), where $f_{(b,d)}$ is a piecewise linear function defined by: + \[ f_{(b,d)} = + \begin{cases} + 0& \text{if }x \notin (b,d)\\ + x-b& \text{if }x\in (b,\frac{b+d}{2})\\ + -x+d& \text{if }x\in (\frac{b+d}{2},d). + \end{cases} + \] +\end{defn} + +The persistence landscape is thus a kind of superposition of piecewise +linear functions. Moreover, one can show that persistence landscapes +are stable with respect to the $L^p$ distance, and that the +Wasserstein and bottleneck distances are bounded by the $L^p$ +distance~\cite{bubenik_statistical_2015}. We can thus view the +landscapes as elements of a Banach space in which we can perform the +statistical computations. + \subsection{Persistence images} +\cite{adams_persistence_2017} + \subsection{Tropical and arctic semirings} +\cite{kalisnik_tropical_2018} + \section{Kernel-based methods}% \label{sec:kernel-based-methods} \subsection{Persistent scale-space kernel} +\cite{reininghaus_stable_2015,kwitt_statistical_2015} + \subsection{Persistence weighted gaussian kernel} +\cite{kusano_kernel_2017} + \subsection{Sliced Wasserstein kernel} +\cite{carriere_sliced_2017} + \section{Comparison}% \label{sec:comparison}