Monthly Archives: April 2009

A Quick Bit of Temporal Logic: Introducing CTL

This post is something that I’m thinking of including in my
book. I haven’t decided whether I want to spend this much time on
logics; they’re really interesting and fun – but there’s lots of
other interesting and fun stuff, and there’s only so much space.

The topic of the moment is temporal logic – that is, a logic which
is built for reasoning about things that change over time.

To begin with, why do we want temporal logic? Most of the time,
when we want to use logical reasoning, we use predicate logic. So why
do we need another logic?

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Yet Another Bible Code Bozo

I’m trying to get back into my routine, after being really devastated by losing my
dog. To people who don’t love dogs, it probably seems silly to be so upset over an animal, but
he was really a member of the family, and losing him really knocked me for a loop.

I’m trying to first get caught up on my book schedule, so I haven’t had time for any
substantial blog posts. But while I was bumming around, a comment showed up on one of my old
posts. For background, several times in the past, I’ve written about the Lords Witnesses, a
Jehovah’s Witness spinoff group that claims to have discovered a “bible code” by which prophecies
are embedded in the bible. They’ve been predicting that Manhattan will be hit by an atomic bomb.
They’ve proposed somewhere around 20 different dates. Their latest prediction was April 4th of
this year.

My last post about the Lord’s Witnesses and their goofy prophesies was back in 2006. But this week, a new comment on that post showed up.

It’s an amusing comment. The gist of it is that he has discovered the
one true bible code; that everyone else who’s found bible codes is really just being
duped by Satan, and that anyone who doesn’t accept the truth of his one true
bible code is an agent of Satan.

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Friday Random Ten

  1. Explosions in the Sky, “Yasmin the Light”: beautiful post-rock.
  2. Kansas, “Miracles Out of Nowhere”: Old Kansas – great stuff.
  3. The Flower Kings, “Starlight Man”: People who’ve read my FRTs know
    that I pretty much worship the ground Roine Stolte walks on. Even a short,
    simple ballad like this, Stolte manages to turn into something amazing.
  4. Metaphor, “Don’t Sleep”: Metaphor is one of my favorite discoveries. They’re
    very obscure; most proggies that I talk to haven’t heard of them. But they’re
    really excellent. Definitely Flower-Kings inspired, but with a very distinctive
    sound, and a great sense of humor.
  5. Flying Bulgar Klezmer Band, “Dig”: Progressive Klezmer! FBKB does
    a fantastic job of mixing very traditional Klezmer with all sorts of other
  6. Tan Dun, “Water Passion after St. Matthew”: This is a masterpiece. Tan Dun
    is a really brilliant composer; this composition is inspired by Bach’s
    “St. Matthew’s Passion”, which is one of my favorite pieces of music of all time.
    It’s frequently difficult to hear the connection between Tan Dun’s work,
    and what inspired it, but the connection is there.
  7. Jerry Douglas, “Takarasaka”: a duet between the world’s best
    Dobro player, and the world’s best Bass player.
  8. Spock’s Beard, “All That’s Left”: SB is a Genesis inspired
    neo-progressive band. They almost dissolved a few years back when their
    original leader quit the band, but since then they’ve developed in
    wonderful directions – they sound much less like they’re trying to just
    be Genesis. This is one of my favorite songs off their most recent album.
  9. Jadis, “What Goes Around?”: Something different: a Marillion inspired
    neo-prog band. They’re on a label run by Steve Rothery from Marillion. They’ve
    got a very Marillion-like sound, but a bit more pop-ish. I still haven’t
    quite decided how I feel about this album.
  10. Genesis, “Fly on a Windshield”: a wonderful bit from Peter Gabriel’s
    masterpiece album with Genesis.

The Return of the Compression Idiot

Remember a while back, I wrote about a crackpot who pestered me both about
converting to Christianity, and his wonderful, miraculous compression system? He
claimed to be able to repeatedly compress any file, making it smaller each time.

Well, he’s back pestering me again. Repeatedly asking him to leave me alone,
shouting at him, etc., hasn’t worked. (His current claim is that he doesn’t know how
to delete me from his gmail contacts list.) So I’m resorting to another round of
public humiliation, which I hope will be informative and entertaining as well.

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The Best Dog in the World is Gone


Things on the blog are probably going to be quiet for a while. My beloved pup, Nutmeg, died last night. He had pancreatic cancer, which had spread to his lungs, liver, and bones. He finally reached the point where even potent medication wasn’t enough to relieve his pain enough, so we had to euthanize him. He died with the entire family
there holding him. I’ve never known another dog like him; he had the most
amazing, wonderful temperament. He was one of the sweetest, gentlest, most loving creatures I’ve ever known. I miss him terribly.

More Deceptive Graphs: Scales Matter

Yet More Deceptive Graphs

As you’ve probably heard, there was a horrible incident in Pittsburgh this weekend, in
which a crazed white supremacist who believed that Obama was coming to take his guns shot and
killed three policemen. Markos Moulitsas, of Daily Kos, pointed out lunatics like this shooter
are acting on conspiracy theories that are being relentlessly promoted by the likes of Glen
Beck and Michelle Bachman. It’s not an unreasonable thing to point out, given the amount of
time that Beck and Bachman have spent lately talking about the impending socialist/fascist
crackdowns that will require a revolutionary response from all right-thinking patriotic

Now, you may think that Kos is an idiot. In fact, even though we agree on many
political issues, I think that Kos is an idiot. I (obviously from what
I wrote above) happen to agree with the basic hypothesis that if you tell
people that the government is going to come and get that and that they need to
defend themselves, that some people are going to believe that the government is
coming to get them and that they need to defend themselves. But the way
that Kos responded was disgusting; it was latching on to a tragic event in
a shallow, snide, heartless way.

But whether you think Kos is an ass ore not isn’t the point. Regardless of your opinion of
the man, there’s no arguing the fact that he’s created a website that draws a really
astonishing amount of traffic, and has become a nexus for many activists on the political

And that, in turn, naturally draws hatred and mockery from the political right. Because,
you see, no one who disagrees with those fine patriotic folks could possibly be an
honest, serious person. They must be a bunch of scheming bastards, obviously.

So, when Kos came out bitching about how the rantings of various crazies really do
have a connection to the actions of people like the Pittsburgh killer, naturally it couldn’t be that he actually believed that people ranting about how the President is
creating a fascistic tyranny that’s going to come take all of your guns could actually
inspire a crazy person to believe that the President creating a fascistic tyranny that was going to come and take away his guns. No, that couldn’t be. He must be up to something – like trawling for hits!

Which, finally, brings us to our topic.

A conservative blogger named Moe Lane posted his theory about why Kos spoke out about the Pittsburgh shooter. It’s because his pageviews have declined so much. But, of course, it wouldn’t be good enough to just say that DKos pageviews are down – he’s got to show that it’s specific to those dirty liberals. So he produces two graphs – one for DKos, and one for RedState, a major conservative site. Here are his graphs; DKos first, Redstate second:


A quick glance shows that both had a huge spike right around the elections, and then they
dropped off pretty dramatically. Then both had a slow upward trend. But the RedState trend
looks a lot steeper.

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Can simulations replace animal testing? Alas, no.

My good friend and blogfather, Orac, posted something yesterday about animal testing
in medical laboratories. I’ve been meaning to write something about that for a while; now
seems like a good time.

I’m not someone who thinks that being cruel to animals is no big deal. I have known
some people like that, but thankfully they’re very rare, and none of them
were scientists whose work involves doing animal testing in real laboratories.

But animal testing isn’t about pointless cruelty. It’s about understanding things that we
simply cannot learn about in any other way. It’s extremely important to minimize the
cruelty we inflict on the subjects of animal tests: there’s no benefit in torturing an animal;
there’s no good reason to inflict unnecessary pain on any living thing. When we
can study something without using animals, we should. When we must use animals
in scientific study, we should be as kind to them as we possibly can. But the fact remains that in many cases, animal studies are necessary.

I don’t want to get into a long discussion of the ethics of it here; that’s a discussion
which has been had hundreds of times in plenty of other places, and there’s really no sense
repeating it yet again. But there is one thing I can contribute to this discussion. One of the
constant refrains of animal-rights protesters arguing against animal testing is: “Animal
testing isn’t necessary. We can use computer simulations instead.”

As a computer scientist who’s spent some time studying simulation, I feel qualified
to comment on that aspect of this argument.

The simplest answer to that is the old programmers mantra: “Garbage in, Garbage out”.

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