IS A CIRCLE AN ELLIPSE in Font

Printer QR-Code in Font IS A CIRCLE AN ELLIPSE

of all possible pay values, that happens to represent the pay for that particular employee. End of aside. Now, some clue as to what Sentence Number 1 might mean when it talks of a circle being derived from an ellipse might perhaps be gleaned from its reference to the opposite possibility ( an ellipse [being] derived from a circle ). By definition, no circle no circle value, that is is just an ellipse (where by the term just an ellipse I mean an ellipse that s not a circle). On the face of it, therefore, to think of an ellipse as being somehow derived from a circle doesn t seem to make any sense at all. Unless and could this be the nub of the matter we allow a circle (which has a = b, remember) to be somehow updated to produce a result with a > b ... Then we might perhaps talk, albeit very loosely, of the ellipse that s the output from that update being derived from the circle that s the input to that update. But when we update something, the thing we update is, by definition, a variable. (To be updatable is to be a variable and vice versa. Certainly we can t update a value! The one thing we can t do to any value is change it because if we could, then after the change it wouldn t be that value any more.) In other words, we might have a variable that currently contains a circle value (with a = b), and we might then update that variable that is, we might replace the current value by another value. And if the value of the variable after the update has a > b, then we might say that the type of the variable was CIRCLE before the update but ELLIPSE after it. And then, as I indicated previously, we might talk, very loosely, of the ellipse value that s the output from the update being derived from the circle value that s the input to the update. Now, I don t know if the foregoing text captures the essence of what Sentence Number 1 is getting at,4 but it does seem plausible, as a hypothesis, to think it does. But observe how much clearer it makes things if we talk explicitly in terms of values and variables! I find it very telling indeed that Sentence Number 1 doesn t mention values or variables at all. And yet the distinction between values and variables is one of the great logical differences! (See Part II of the present book in particular, see 6 for further elaboration of this useful and important concept.) Sadly, it s also one that s very much overlooked I m tempted to say totally ignored in the object world, a point I ll come back to later. 2. The often-heard arguments because that s the way it is in mathematics and because the representation of a circle is a subset of that of an ellipse are not conclusive and most often wrong. The two often-heard arguments quoted here are very different in kind. The first ( because that s the way it is in mathematics ) I would have rephrased as because that s the way it is in the real world. If someone wants to propose a world in which circles aren t ellipses, then all I can say is that the person in question must be using the terms circle and ellipse in ways that fly in the face of their conventionally accepted meanings. In other words, I find this first argument, far from being inconclusive and wrong, both conclusive and right. The second argument ( because the representation of a circle is a subset of that of an ellipse ) is rather different, however. In fact, it demonstrates a confusion again one that seems to be all too common in the object world between type and representation. Type vs. representation is another of the great logical differences! In database contexts, at least (and, I would argue, in other contexts too, desirably), we try to distinguish carefully between a type, on the one hand, and the representation of values of that type inside the system, on the other.