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Space Time Hierachy

Last edited: August 8, 2025

I finally get to sound like I’m doing physics.

\begin{equation} L \subseteq P \subseteq \text{PSPACE} \subseteq \text{EXP} \end{equation}

by space hierarchy theorem and time hierarchy theorem, we have also that:

\begin{equation} \text{P} \subset \text{EXP} \end{equation}

and

\begin{equation} L \subset\text{PSPACE} \end{equation}

so we know that one of the subset things on top is a strict subset. There’s also a bridge \(P \subseteq \text{NP} \subseteq \text{PSPACE}\).

\(L =^{?} P\)

We believe that \(L \subset P\), but we can’t show this.

span (linear algebra)

Last edited: August 8, 2025

The span of a bunch of vectors is the set of all linear combinations of that bunch of vectors. We denote it as \(span(v_1, \dots v_{m)}\).

constituents

requirements

\begin{equation} span(v_{1}..v_{m}) = \{a_1v_1+\dots +a_{m}v_{m}:a_1\dots a_{m} \in \mathbb{F}\} \end{equation}

additional information

span is the smallest subspace containing all vectors in the list

Part 1: that a span of a list of vectors is a subspace containing those vectors

spanish

Last edited: August 8, 2025
  1. Órale pues: confirmando
  2. No hay pedo: no hay problema
  3. Ponte la de puebla: dividirlo
  4. Qué padre: sopresa positiva
  5. De a grapa: gratis
  6. De poca madre: júbilo y aceptación
  7. Te vas a dar un ranazo: nos vamos a hacer daño (hurt)

Mamá: ¡necesitamos limpiar sus cuartos! Me: órale pues, no hay pedo. Voy a limpiarlo mañana.

Mi plan está simple. Voy a dividir mi cuarto a media, y contrata mi amiga para ayudarme. ¡Ponte la de puebla!

Spark

Last edited: August 8, 2025

Spark is not a database. Importantly, its a “framework” of data:

  • Programming platform
  • Distributed file system
  • Prallel execution environment
  • Software ecosystem

It gives you the “parallel” search/sort needed to navigate a large database. It is based on the Hadoop ecosystem. Spark operates on RDDs to do lazy-evaluation.

Quickstart

When we start up Spark Shell, it will build you a sc variable which is appropriate for your supercomputer; if you are not, you need to set up the context yourself using the 3 lines noted below to make sc variable:

Sparse Sampling

Last edited: August 8, 2025

Same core algorithm as Forward Search, but instead of calculating a utility based on the action-value over all possible next states, you make \(m\) different samples of next state, action, and reward, and average them