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And a pseudohybrid 7x7 puzzle (with AND and XOR operators)
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Posted on: Mon Dec 05, 2011 1:04 am

Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
starling wrote:
... I actually explicitly had one teacher tell me that none of my answers on past tests are wrong, but he wouldn't be giving me credit back).

Probably that "dangerous" teacher thinks in this way: Ok, this solution for the problem is correct but since there are many solutions I will not assign any credit to it.

starling wrote:
Anyhow, basically, it's between hard and impossible to write a difficult no-op that doesn't have multiple solutions. If it has one solution, it's probably easy. If it's hard, it probably has multiple solutions.

Better let's say between very hard and almost impossible (accepting that premise that nothing is impossible , I thought it was impossible to go under 5 seconds for a timed 4x4!) but certainly to prove the unicity we would need the computer, as Patrick mentions, with the appropriate software, my actual intuition is that we might obtain those puzzles with a reasonable level of difficulty (not trivial).

Posted on: Mon Dec 05, 2011 2:14 am

Posts: 175
Joined: Fri May 13, 2011 2:11 am
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
clm wrote:
starling wrote:
... I actually explicitly had one teacher tell me that none of my answers on past tests are wrong, but he wouldn't be giving me credit back).

Probably that "dangerous" teacher thinks in this way: Ok, this solution for the problem is correct but since there are many solutions I will not assign any credit to it.

Wouldn't be a problem if he weren't a math teacher. Then it's a problem.

Posted on: Mon Dec 05, 2011 5:41 am

Posts: 422
Joined: Fri May 13, 2011 2:43 am
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
starling wrote:
Anyhow, basically, it's between hard and impossible to write a difficult no-op that doesn't have multiple solutions. If it has one solution, it's probably easy. If it's hard, it probably has multiple solutions.

See the No-op topic. It wasn't hard to make it. Or else I got lucky. Granted, it's not very hard, but it's a 5x5... thought we could start somewhere.

Posted on: Sun Dec 11, 2011 3:34 pm

Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
pnm wrote:
clm wrote:
Thank you, here is the code for the 7x7 pseudohybrid puzzle (arithmetic and logic operators), however I have observed that you are using the same symbol, ^, for the operation XOR than for the exponentiation (previous topic 7x7 hybrid with all operators), I assume it's Ok:

Hm, you're right, I'll have to figure something out.

The ^ for XOR is borrowed from C, the ^ for exponentiation from LaTeX ..

Patrick

Hi, Patrick, I have observed that some other computer languages duplicate the symbols, for instance, "||" for the biwise OR, "&&" for the AND function and "^^" for the bitwise XOR. You use a single symbol "|" for the bitwise OR, "&" for the AND, "%" for the mod function (that appears as a literal "mod" in the puzzle itself), etc. Since you already use the single "^" symbol for the exponentiation perhaps using the double "^^" for the XOR would create problems. I suggest to replace by the "\$" for the XOR (single, following your philosophy) and, in the future, if other operators are introduced, like the NOT, XNOR, etc., we would see at that time, but I do not know what kind of problems you may find with all this in your software.

Posted on: Mon Dec 12, 2011 11:30 am

Posts: 2209
Joined: Thu May 12, 2011 11:58 pm
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
clm wrote:
pnm wrote:
The ^ for XOR is borrowed from C, the ^ for exponentiation from LaTeX ..

Hi, Patrick, I have observed that some other computer languages duplicate the symbols, for instance, "||" for the biwise OR, "&&" for the AND function and "^^" for the bitwise XOR

There's || for the logical OR, and && for logical AND (in conditions) in C and
all derived languages (which are most of the popular programming languages, if not all)
(not sure if ^^ exists). The single-characters versions are the bitwise operators.

Patrick

Posted on: Fri Dec 16, 2011 4:08 pm

Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Re: And a pseudohybrid 7x7 puzzle (with AND and XOR operator
pnm wrote:
clm wrote:
pnm wrote:
The ^ for XOR is borrowed from C, the ^ for exponentiation from LaTeX ..

Hi, Patrick, I have observed that some other computer languages duplicate the symbols, for instance, "||" for the biwise OR, "&&" for the AND function and "^^" for the bitwise XOR

There's || for the logical OR, and && for logical AND (in conditions) in C and
all derived languages (which are most of the popular programming languages, if not all)
(not sure if ^^ exists). The single-characters versions are the bitwise operators.

Patrick

Ok, then, Patrick, what do you think about testing this special 7x7 puzzle, may we assign any specific symbol to that "bitwise XOR" operation for your solver?

Posted on: Sun Jan 08, 2012 3:14 pm

Posts: 693
Joined: Fri May 13, 2011 6:51 pm
Re: And a pseudohybrid 7x7 puzzle, with AND and XOR operator
This particular example does not contain the "NOT" logic operator but this operator could also be included to complete a full set of logic operations.

Here is the solution for this "pseudohybrid 7x7" (though unfortunately we could not finally test it for the unicity of the solution):

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