note Plankton <p> I think you are trying to say a "but" operator is equivalent "not and" operator and that !(A->B) is equivalent to "but". I am assuming that "!" symbolizes the negation operator and "->" symbolized the if-then ( or implies ) operator. </p><p> Yet ... <table border=1> <tr><th>P</th><th>Q</th><th>P->Q</th><tr> <tr><td>T</td><td>T</td><td>T</td></tr> <tr><td>T</td><td>F</td><td>F</td></tr> <tr><td>F</td><td>T</td><td>T</td></tr> <tr><td>F</td><td>F</td><td>T</td></tr> </table> </p><p> <table border=1> <tr><th>P</th><th>Q</th><th>P and Q</th><th>!(P and Q)</th></tr> <tr><td>T</td><td>T</td><td>T</td><td>F</td></tr> <tr><td>T</td><td>F</td><td>F</td><td>T</td></tr> <tr><td>F</td><td>T</td><td>F</td><td>T</td></tr> <tr><td>F</td><td>F</td><td>F</td><td>T</td></tr> </table>So I would say "A and !B"is not equivalent to "!(A -> B)" and I wouldn't say "A but B" <=> "A and !B", but I could just be misunderstanding your notation. :) </p><p> As far a what a but operator is I would say it should be equivalent to the "Boolean And" operator. And is not needed in a programming language. The word "but" is used in commonly to emphasis that an assumption is false. Example ... <pre> If a student where to errorously assume that multiplaction is the same as addition the student might state ... 1 + 1 = 2 and 2 + 2 = 4 and 2 * 2 = 4 and 1 * 1 = 2 ... which we know to be false. The student's teacher would say ... 1 + 1 = 2 and 2 + 2 = 4 and 2 * 2 = 4 but 1 * 1 != 2 ... to correct the student. This is the same as 1 + 1 = 2 and 2 + 2 = 4 and 2 * 2 = 4 and 1 * 1 != 2 T and T and T and T is TRUE It is not equal to 1 + 1 = 2 and 2 + 2 = 4 and 2 * 2 = 4 and not (1 * 1 != 2) T and T and T and F is FALSE </pre> </p><p> But merely gives emphasis to the fact that the student's assumption is false. </p> <p><font size=-2>[Janitors|Janitored] by [davido]: removed excess spaces within pre tags that caused horizontal scrolling.</font></p> <!-- Node text goes above. Div tags should contain sig only --> <div class="pmsig"><div class="pmsig-290288"> <BR><TABLE><TR><TD bgcolor=lightgreen>Plankton: 1% Evil, 99% Hot Gas.</TD></TR></TABLE> </div></div> 394269 394282