boolean-expression

I want to parse user values contained in .CSV file. I don't want my users to enter "Yes" or "No" but instead enter "True" or "False". In each case I want to convert to the equivalent boolean values: $true or $false . Ideally I would like a default value, so if there's misspelt "Yes or "No" I would return my default value: $true or $false . Hence, I wondered if there is a neat way of doing this other than if(){} else (){} One way is a switch statement: $bool = switch ($string) { 'yes' { $true } 'no' { $false } } Add a clause default if you want to handle values that are neither "yes" nor "no":

Is it pythonic to use or , similar to how PHP would use or die() ? I have been using quiet or print(stuff) instead of if verbose: print(stuff) lately. I think it looks nicer, they do the same thing, and it saves on a line. Would one be better than the other in terms of performance? The bytecode for both look pretty much the same to me, but I don't really know what I'm looking at... or 2 0 LOAD_FAST 0 (quiet) 3 JUMP_IF_TRUE_OR_POP 15 6 LOAD_GLOBAL 0 (print) 9 LOAD_CONST 1 ('foo') 12 CALL_FUNCTION 1 (1 positional, 0 keyword pair) >> 15 POP_TOP 16 LOAD_CONST 0 (None) 19 RETURN_VALUE vs if 2 0

Anybody knows of an algorithm to simplify boolean expressions? I remember the boolean algebra and Karnaught maps, but this is meant for digital hardware where EVERITHING is boolean. I would like something that takes into account that some sub-expressions are not boolean. For example: a == 1 && a == 3 this could be translated to a pure boolean expression: a1 && a3 but this is expression is irreducible, while with a little bit of knowledge of arithmetics everibody can determine that the expression is just: false Some body knows some links? You might be interested in K-maps and the Quine

I've written a little app that parses expressions into abstract syntax trees. Right now, I use a bunch of heuristics against the expression in order to decide how to best evaluate the query. Unfortunately, there are examples which make the query plan extremely bad. I've found a way to provably make better guesses as to how queries should be evaluated, but I need to put my expression into CNF or DNF first in order to get provably correct answers. I know this could result in potentially exponential time and space, but for typical queries my users run this is not a problem. Now, converting to CNF

Its the same thing right? Or is there a slight difference? I just wanna make sure I'm not misunderstanding anything. J.C.Morris Boolean duals are generated by simply replacing ANDs with ORs and ORs with ANDs. The complements themselves are unaffected, where as the complement of an expression is the negation of the variables WITH the replacement of ANDs with ORs and vice versa. Consider: A+B Complement: A'B' Dual: AB "The Dual of an identity is also an identity. This is called the Duality Principle". A Boolean Identity is X+0=X or X+X=X. There's lots of them. Duals only work with identities. To