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| Applying the enlargement operator <math>\operatorname{E}</math> to the present example, <math>f(x, y) = xy,\!</math> we may compute the result as follows: | | Applying the enlargement operator <math>\operatorname{E}</math> to the present example, <math>f(x, y) = xy,\!</math> we may compute the result as follows: |
| | | |
− | {| align="center" cellpadding="6" style="text-align:center" width="90%" | + | {| align="center" cellpadding="6" width="90%" |
− | | | + | | align="center" | |
| <math>\operatorname{E}f(x, y, \operatorname{d}x, \operatorname{d}y) \quad = \quad (x + \operatorname{d}x)(y + \operatorname{d}y).</math> | | <math>\operatorname{E}f(x, y, \operatorname{d}x, \operatorname{d}y) \quad = \quad (x + \operatorname{d}x)(y + \operatorname{d}y).</math> |
| |- | | |- |
− | | | + | | align="center" | |
| <pre> | | <pre> |
| o---------------------------------------o | | o---------------------------------------o |
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| |} | | |} |
| | | |
− | <pre>
| + | Given the proposition <math>f(x, y)\!</math> in <math>U = X \times Y,</math> the (first order) ''difference'' of <math>f\!</math> is the proposition <math>\operatorname{D}f</math> in <math>\operatorname{E}U</math> that is defined by the formula <math>\operatorname{D}f = \operatorname{E}f - f,</math> that is, <math>\operatorname{D}f(x, y, \operatorname{d}x, \operatorname{d}y) = f(x + \operatorname{d}x, y + \operatorname{d}y) - f(x, y).</math> |
− | Given the proposition f(x, y) in U = X x Y, | |
− | the (first order) 'difference' of f is the | |
− | proposition Df in EU that is defined by the | |
− | formula Df = Ef - f, or, written out in full, | |
− | Df(x, y, dx, dy) = f(x + dx, y + dy) - f(x, y).
| |
| | | |
− | In the example f(x, y) = xy, the result is: | + | In the example <math>f(x, y) = xy,\!</math> the result is: |
− | | |
− | Df(x, y, dx, dy) = (x + dx)(y + dy) - xy.
| |
| | | |
| + | {| align="center" cellpadding="6" width="90%" |
| + | | align="center" | |
| + | <math>\operatorname{D}f(x, y, \operatorname{d}x, \operatorname{d}y) \quad = \quad (x + \operatorname{d}x)(y + \operatorname{d}y) - xy.</math> |
| + | |- |
| + | | align="center" | |
| + | <pre> |
| o---------------------------------------o | | o---------------------------------------o |
| | | | | | | |
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| | Df = ((x, dx)(y, dy), xy) | | | | Df = ((x, dx)(y, dy), xy) | |
| o---------------------------------------o | | o---------------------------------------o |
| + | </pre> |
| + | |} |
| | | |
| + | <pre> |
| We did not yet go through the trouble to interpret this (first order) | | We did not yet go through the trouble to interpret this (first order) |
| "difference of conjunction" fully, but were happy simply to evaluate | | "difference of conjunction" fully, but were happy simply to evaluate |