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ONT Re: Differential Logic




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DLOG.  Note D73

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Transformations of Type B^2 -> B^2

To take up a slightly more complex example, but one that remains
simple enough to pursue through a complete series of developments,
consider the transformation from U% = [u, v] to X% = [x, y] that is
defined by the following system of equations:

o-----------------------------------------------------------o
|                                                           |
|         x   =   f(u, v)   =   ((u)(v))                    |
|                                                           |
|         y   =   g(u, v)   =   ((u, v))                    |
|                                                           |
o-----------------------------------------------------------o

The component notation F = <F_1, F_2> = <f, g> : U% -> X% allows
us to give a name and a type to this transformation, and permits
us to define it by means of the compact description that follows:

o-----------------------------------------------------------o
|                                                           |
|    <x, y>   =   F<u, v>   =   <((u)(v)), ((u, v))>        |
|                                                           |
o-----------------------------------------------------------o

The information that defines the logical transformation F can be represented
in the form of a truth table, as in Table 60.  To cut down on subscripts in
this example I continue to use plain letter equivalents for all components
of spaces and maps.

Table 60.  A Propositional Transformation
o-------------o-------------o-------------o-------------o
|      u      |      v      |      f      |      g      |
o-------------o-------------o-------------o-------------o
|             |             |             |             |
|      0      |      0      |      0      |      1      |
|             |             |             |             |
|      0      |      1      |      1      |      0      |
|             |             |             |             |
|      1      |      0      |      1      |      0      |
|             |             |             |             |
|      1      |      1      |      1      |      1      |
|             |             |             |             |
o-------------o-------------o-------------o-------------o
|             |             |  ((u)(v))   |  ((u, v))   |
o-------------o-------------o-------------o-------------o

Jon Awbrey

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