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seen 7 hours ago

Jul
2
awarded  Curious
Jun
27
comment what's a homogeneous transformation?
@PeterFranek I've edited in the context of the question
Jun
27
revised what's a homogeneous transformation?
clarify context of question
Jun
27
asked what's a homogeneous transformation?
Apr
23
awarded  Tumbleweed
Apr
16
revised How does invariance of $q$ wrt $\lambda$ for a stationary functional, restrict the function?
changed heading, added tags
Apr
16
asked How does invariance of $q$ wrt $\lambda$ for a stationary functional, restrict the function?
Apr
7
awarded  Popular Question
Mar
1
asked Can the Euler-Lagrange equations be derived from a variation over a time of order $dt$ rather than $t$?
Feb
22
comment Does every continuous function have a left and right derivative?
I wouldn't have believed it was possible at the time
Feb
21
accepted Does every continuous function have a left and right derivative?
Feb
21
asked Does every continuous function have a left and right derivative?
Nov
21
comment Is invariance of a multi-linear form required for co/contra variance?
I was trying to help you get to answering the point of my question, it wasn't meant to be an interrogation ;) So let me put it another way: what calculation do we perform on the components of a tensor that makes it "invariant"? I suspect we create a multilinear form from its components and its dual tensor, and this is an invariant. BTW, I'm learning tensors from scratch using this book, so pardon my ignorance.
Nov
20
comment Is invariance of a multi-linear form required for co/contra variance?
Is the multilinear form in the OP quote always invariant to a change in coordinates: yes or no?
Nov
15
awarded  Promoter
Nov
14
revised Is invariance of a multi-linear form required for co/contra variance?
removed unnecessary tag
Nov
13
asked Is invariance of a multi-linear form required for co/contra variance?
Oct
24
awarded  Notable Question
Sep
26
comment Cartesian products of families in Halmos' book.
I had exactly the same problem understanding the idea from an old topology book by Burgess, influenced by Halmos. This answer clarifies things so thanks.
Sep
25
asked What's meant by “a family $\{A_i\}$ of subsets of $X$”