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Apr
16
asked Original publication of P.A.M. Dirac
Mar
26
awarded  Tumbleweed
Mar
26
accepted Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
Mar
26
comment Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
Thank you for the clarification. Does NSA use an infinitesimal $\epsilon$ with $\epsilon^2 = 0$? And how would SIA look at $\epsilon^2 / \epsilon^2$ ?
Mar
26
awarded  Commentator
Mar
26
comment Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
I see. What is the difference between 1) smooth infinitesimal analysis (SIA) 2) nonstandard analysis and 3) hyperreal numbers?
Mar
19
asked Why is it that quadratic forms seem fundamental for reciprocal or dual mappings?
Mar
18
comment What is a very simple example of the way projective geometry is used in quantum mechanics?
Question regarding the projective ray characteristic: "differing in phase, that is, differing by multiplication by a scalar". In QM the multiplicative factor has absolute value 1 (phase factor), however in PG the multiplicative factor is free, except 0 is not allowed. Correct? What does this difference imply?
Mar
16
revised Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
added 195 characters in body; edited tags
Mar
16
comment Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
W.r.t. hyperreals, I probably misformulated, I meant nilsquare infinitesimals, edited my question.
Mar
16
comment Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
Sorry, I am not currently able to understand your answer ...
Mar
15
revised Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
added 189 characters in body
Mar
15
asked Is $\epsilon^2/\epsilon^2=1$ or $0/0$?
Feb
18
accepted Which 6x6 line-matrix corresponds to a 4x4 point/plane-matrix
Feb
15
asked Which 6x6 line-matrix corresponds to a 4x4 point/plane-matrix
Jan
27
accepted Wild automorphisms of the complex numbers
Jan
26
awarded  Nice Question
Oct
28
accepted Distinguishing projective collineations with/without an underlying field-automorphism
Oct
27
comment Distinguishing projective collineations with/without an underlying field-automorphism
This seems very logical, but how about the mapping $f: z \rightarrow \bar{z}$? The anti-projective collineation is clearly: identity+complex conjugation. Which projective collineation (without complex conjugation) would then belong to this mapping?
Oct
27
revised Distinguishing projective collineations with/without an underlying field-automorphism
deleted 2 characters in body