Guidance: Convex hull, null space and convex basis etc

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Discussion Overview

The discussion revolves around foundational mathematical concepts related to convex sets, including the convex hull, convex basis, convex combinations of vectors, and null space, in the context of a research paper on robotic grasp closure properties. Participants seek clarification and resources for better understanding these terms.

Discussion Character

  • Exploratory, Conceptual clarification, Homework-related

Main Points Raised

  • One participant expresses confusion about terms like 'convex hull', 'convex basis', and 'null space', seeking guidance on where to start learning about these concepts.
  • Another participant suggests using online resources to look up the terms.
  • A different participant explains that a convex set in R^n is defined by the property that any line segment between two points in the set also lies within the set, and describes the convex hull as the smallest convex set containing a given set.
  • This participant also provides a definition of null space in the context of linear transformations, stating it consists of all vectors that map to zero.
  • Another participant defines a convex basis as a set of vectors that can be combined with positive weights to form convex combinations.

Areas of Agreement / Disagreement

There is no consensus on the definitions of all terms, as some participants express uncertainty about specific concepts like 'convex basis' and 'free space'. The discussion remains unresolved regarding the best resources for learning.

Contextual Notes

Participants have varying levels of familiarity with the mathematical terms discussed, and there may be missing assumptions regarding the definitions and applications of these concepts.

Inner_Peace
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Hi friends!
I am getting started with a research paper that discusses the closure properties of a robotic grasp. There are of lot of mathematical terms that confuse me like 'convex hull' , convex basis, convex combination of vectors, a free subset, nullspace etc. I might have studied some of them in University mathematics but that seems a long ago. Could you please suggest me places where should I start looking for concept building ? Any good tutorials or books?

Thank you ! :)
 
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Have you tried to google these terms?
 
I don't see this as having much to do with vectors. A "convex set" in [itex]R^n[/itex] is a set such that for any two points p and q in the set the line segment between p and q is in the set also.

The "convex hull" of a set, A, is the smallest convex set that has A as a subset. One way to construct the convex hull of a set is to add all line segments between any two points in the set.

I don't recognize the terms "convex basis", "convex combination", or "free space".

The "null space" of a linear Transformation, T, from one vector space to another, is the set of all vectors, v, such that T(v)= 0. One can show that the null space is a subspace of the domain vector space.
 
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Amazon.com has several books on the subject. You will need to look at the reviews to see what fits your needs.
A convex basis is a set of vectors that can be added together with positive weights (all weights 0<=w<=1 that sum to 1). Those weighted sums are the convex combinations.
 
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