# Photos from The Netherlands, I

The Sunday before Elena's defense, I went sightseeing in Waterland in The Netherlands (more specifically Marken and Monnickendam, followed by a brief visit to Naarden) with Marc, Bettina, and Elena. It was very pretty, but very wet. After the ALGO conferences ended today I had time to process my photos, and also threw in some from a later visit to Nuenen (birthplace of Van Gogh and the setting for several of his paintings).

The full gallery is here. I still have many more photos to process, so more is to come.

SAT is (not) NP-complete

http://arxiv.org/abs/0806.2947

Here is a easy-to-understand for this:

Let L be the Prolog program:

Fact:

Age-About-21(John,0.9).

Goal:

?- Age-About-21(John,0.9).

The Prolog system answers two different contradictory answers:

"Yes" = "1" and "0.9" in the fact.

Try the goal:

?- Age-About-21(John,0.3).

Again, the system answers two contradictory answers:"No" = "0" and "0.9".

Clearly, this language is in P, but how to reduce it to SAT?

How to reduce instances of the FLP problem whose output is two contradictory truth values to the SAT problem whose output is only one.

It is easy to show that ZFC is inconsistent via 2 (independent) proofs.

77.245.14.116, does your crankery have anything to do with sightseeing in the Netherlands?

The full gallery is here. I still have many more photos to process, so more is to come.

### Comments:

**None**: SAT is (NOT) NP-complete

**2008-09-26T16:56:37Z**

SAT is (not) NP-complete

http://arxiv.org/abs/0806.2947

Here is a easy-to-understand for this:

Let L be the Prolog program:

Fact:

Age-About-21(John,0.9).

Goal:

?- Age-About-21(John,0.9).

The Prolog system answers two different contradictory answers:

"Yes" = "1" and "0.9" in the fact.

Try the goal:

?- Age-About-21(John,0.3).

Again, the system answers two contradictory answers:"No" = "0" and "0.9".

Clearly, this language is in P, but how to reduce it to SAT?

How to reduce instances of the FLP problem whose output is two contradictory truth values to the SAT problem whose output is only one.

It is easy to show that ZFC is inconsistent via 2 (independent) proofs.

**11011110**: Re: SAT is (NOT) NP-complete

**2008-09-26T17:17:47Z**

77.245.14.116, does your crankery have anything to do with sightseeing in the Netherlands?

**None**: Re: SAT is (NOT) NP-complete

**2008-09-27T10:41:05Z**

Posted by mistake.

I deeply apologize.

Never mind the proof of SAT being (not) NP-complete would render ZFC inconsistent which may indirectly affect lots of things; not just sight-seeing in the Netherlands.

Review the paper, it has several proofs, none of which is about the mathematical foundations of sight-seeing.

Please accept my apologies again.