Cross Entropy Method
Last edited: August 8, 2025This method introduces a search distribution instead of discrete points:
\begin{equation} p(\theta | \psi) \end{equation}
We want to know how parameters \(\theta\) are distributed, given some input parameters \(\psi\) (for instance, we assume parameters are gaussian distributed such as the mean/variance).
- Given this distribution, we sample \(m\) samples of \(\theta\) from the distribution. Those are our starting candidate points.
- We then check its policy for its utility via the Roll-out utility
- We want to take top \(k\) of our best performers, called “elite samples” \(m_{elite}\)
- Use the set of \(m_{elite}\) points, we fit a new distribution parameter \(\psi\) that describes those sample
This allows us to bound how many Roll-out utilities we are doing.
cross product
Last edited: August 8, 2025constituents
additional information
lack of inverse of cross product
The cross product doesn’t have an inverse
geometric interpretation of cross product
\begin{equation} a \times b = |\vec{a}| |\vec{b}| \sin \theta n \end{equation}
where, \(n\) is the unit vector in some direction.
The length of the resulting vector in the cross product is the area of the parallelogram formed by the two vectors.
CrossFinder
Last edited: August 8, 2025CrossFinder is a darkpool owned by Credit Suisse.
Features:
- Normal darkpooling
- Routing the transaction out to other exchanges and dark-pools if needed
- Measuring the latency of each other exchange, etc.
cryo-electron microscopy
Last edited: August 8, 2025cyro-EM is a structure determination system of a solution (Dutta, M. 2018. J indian inst sci 98) to analyze a structural population of particles from TEM; the resulting 3-D structures obtained can be analyzed and classified.
“The Resolution Revolution”: much better structures to analyze because of high-fidelity cyro-EM
cyro-EM vs x-ray crystallography
cyro-EM can identify heterogeneous motions throughout the structure, instead of averaging out multiple structural combinations; instead of the “general” structure on average, we can get a collection of various states the particle can be in.
