> Am 26.02.2018 um 16:12 schrieb Lawrence Paulson <l...@cam.ac.uk>:
> I was at the meeting in LogroƱo and my impression was that we had to live 
> with these different formalisations. There was no way to unify them and the 
> best one could hope to transfer certain results from one formalisation to 
> another using local types in some incredibly complicated way.
HMA_Connect shows a way to unify (at least parts of) them: it makes explicit 
that 'a^'n^'m can be seen as a subtype of 'a mat.

This makes it possible to avoid duplications: for example, results about 
eigenvalues are only proved once for 'a mat and are transferred to the 
"subtype" 'a^'n^'m.
In contrast to that, we do have duplicate developments for determinants, 
multiplication etc. in isabelle and the AFP. We should be able to get rid of 

Ideally, one would do the developments for 'a^'n^'m, but I am not sure how well 
theorems can be transferred in that direction...


> If there really is a common basis for formalising linear algebra than I would 
> be thrilled to see it, and I'm sure we could figure out a way to implement 
> this.
> Larry
>> On 26 Feb 2018, at 14:57, Fabian Immler <imm...@in.tum.de 
>> <mailto:imm...@in.tum.de>> wrote:
>> We do have the problem that AFP/Jordan_Normal_Form/Matrix and 
>> Analysis/Finite_Cartesian_Product both formalize vectors and matrices and 
>> that there are formalizations of (aspects of) linear algebra for both of 
>> them. Last year in Logrono, there was the proposal to put all linear algebra 
>> on the common foundation of a locale for modules, but apparently nobody has 
>> found the time and motivation to push this much further.
>> Perhaps a more humble first step towards unifying the existing theories 
>> would be to move AFP/Jordan_Normal_Form/Matrix to the distribution and do 
>> the construction of Finite_Cartesian_Product.vec as a subtype of Matrix.vec.
>> Any opinions on that?

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