Better Temporally than Existentially Late

I am not a slow driver, although I am certainly not a speed demon either. My philosophy is that speed limits exist for a good reason -- safety.

I obey the speed limit near schools, for example, because there are a lot of children around and I don't want to hurt anyone. At a lower speed I have a better chance of being able to stop if a person runs into the road -- and a lower chance of hurting them if I'm unable to stop. I also obey the speed limit on busy residential streets, a behavior that is somewhat influenced by having lived on a busy street myself for more than six years.

Sometimes, particularly on the open road or a limited access highway, I have been known to speed -- rarely more than ten mph above the speed limit, but definitely above the marked limit. I've also driven well above the speed limit and (I must admit) somewhat recklessly when I believed that my passenger was having a heart attack and needed to get to the hospital RIGHT AWAY. And Jeff drove like a maniac to the hospital when Vinny and I sped away in an ambulance after our week-old son stopped breathing.

But if I'm late to work, or to an appointment? Not gonna speed. I'd rather be temporally late than existentially late, as it were. My life and the lives of those around me are too precious to risk on the possibility that I will be punished or miss part of an appointment. I'd rather step into the movie theater five minutes late than not step into it at all.

All this was brought up in my mind earlier this evening when someone in a hurry felt compelled to pass me despite my 50 mph in a 45 zone, the wet, slippery road, and the double yellow line prohibiting passing. I slowed down a bit to let him by, and waved as he passed. I hope he got to his destination safely and soundly, especially if there was an emergency.

Happy Anniversary to Us!

Today marks the eleventh anniversary of the date that Jeff and I got married. How are we celebrating it? By going to a wedding!

My cousin is getting married today. I think it's a perfect day for a wedding. Hopefully she will share not only the date with us, but also the lifetime of good memories as well.

Tired

Please, may I have some sleep?

Critters and Nature

My workplace is pretty far out in the middle of nowhere, within tens of thousands of acres of nature preserve. That's pretty cool and all, but there are a few downsides.

The first one is that since it's out in the middle of nowhere, you have to drive to work. My commute is 10.5 miles each way, and I live (relatively) nearby. There are a few hard-core folks who bike in, and I admire them, but there's no way I can do that at the present time.

The second thing is both good and bad: there's a lot of nature in them there nature preserves. So you see a lot of wildlife, which is cool. But that also means you have to coexist with a lot of wildlife, so you have to be extra careful while driving, especially at dawn or dusk, and you can't just leave trash bags lying around, for example.

I'd say I see a deer at least once a week, more often during the winter mating season. I've seen a lot of turkey vultures lately. And there are an awful lot of other critters too. You can see some evidence of some wild creatures in these prints on the side of a dumpster I walk past every day:



including some raccoons (at the bottom) and a wild creature of the totally fake variety* in the center of the picture.


* I don't know who made that print but when I first walked past it and caught it out of the corner of my eye, I thought, "wow, do we have bears or something really big living here?" But once I actually looked at it I quickly realized that it was a prank.

Not a Guy

I am not a guy.

Because I am not a guy, I hate it when people refer to members of my profession as "math guys." As in, "You should ask one of the math guys." Or "Those math guys sure are ugly."

"But Rebecca," you say. "Guy is a gender-neutral term."

No, it's not. If somebody walked into a room full of people and asked to speak to someone who possesses expert knowledge about optimization, supercomputing, and ulnar nerve entrapment, would you point in my general direction and say, "You need to talk to that guy over there, in the turquoise blouse"? No, you wouldn't, because I am not a guy. Guy is not a gender-neutral term, just like man is not a gender-neutral term.

Guys I can excuse when it is part of "you guys." That is an expression in the English language. Personally, I always say y'all, because I hate the term "guys," but I can overlook "you guys."

"But Rebecca," you say. "They are math guys. In this particular group, there actually aren't any women."

Fine, but you should call them "math folks" or "math group" or "math people" instead of "math guys" no matter the gender balance, unless you're trying to distinguish this particular group by using their gender to set them apart from other groups. While they may all be guys, possessing the "guy property" is not required in order to possess the "math property." Out of respect for the fact that those who are not guys could be members of the group, you should not use guys.

As a more obvious example, you could label them as the "math white people," because chances are good that they're all white. But you can easily see that "white people" is not necessary, because there are people of all races and ethnicities who are skilled in math. Like a race marker is not necessary in describing the group of mathematicians, a gender marker isn't needed either.

I hope that I have now convinced you, my vast readership, to use words such as folks, group, or people rather than guys when describing a collective group of people that may be composed of members of both sexes. If not, then please don't ever talk to me about groups of people, or I may feel inclined to puke on your shoes.

Weather Update

The weather over the weekend was absolutely beautiful. It was sunny but cool -- I don't think the temperature ever got to 80º F! It reminded me of September more than July.

I kept the windows open all weekend. I really enjoy fresh air, and it's a rare treat that you can comfortably open your windows in July. I'm glad I got the chance this weekend!

Lime Sublime

I just wanted to do a little shout-out to the lime.

Lime is an under-appreciated fruit and flavor. It is my opinion that a little lime juice can give your food the kick that it needs.

The first time I realized this was when I went to a local Thai restaurant and ordered some fried rice. It came with a lime wedge which I squeezed over my rice. Without the lime, it was pretty good. But with the lime, it was positively heavenly! Somehow, adding the lime just unified all the flavors in the dish. I can't explain it. All I know is that every time I go to that restaurant I order that same dish, and am never disappointed.

I also add lime juice to my delicious and easy-to-make pozole: a whole chicken, cut into pieces and grilled (or at least browned in the frying pan), a gigantic can of hominy, a gigantic can of whole tomatoes, chicken broth, 1 lb. of sweet corn kernels, one pound of cut carrots, bay leaves, rosemary, and lime juice. Without the lime juice, it's just not as good.

Last weekend, I was making some blueberry sauce* for the waffles Vinny and I were making (see, EcoGeoFemme, we're branching out!), and I couldn't find the lemon juice, so I substituted lime juice instead. Boy, did that make the blueberry sauce even better! I made some more yesterday (once again for mother-son waffles -- he's really into the red and green lights indicating the status of your waffle, plus the squares in the waffle iron) and used lime juice on purpose, just because I liked the extra zing it gave.

Anyhow, I just wanted to sing the praises of lime and encourage everybody to try it out if you have not yet.


* From The Joy of Cooking (of course!): Combine in a saucepan over medium heat 1 pint fresh blueberries, 1/3 c sugar, 3T lemon juice, and stir constantly. After it cooks down add a solution of 1T water + 1.5t corn starch and boil for 1 minute.

Jimmy Carter, You Are My New Hero

When I read this article by Jimmy Carter, I wanted to cry for joy. Here is a man who gets it.

In the article, Carter explains why he severed ties with the Southern Baptist Convention -- because they were systematically selecting to emphasize Bible verses to support the subjugation of women. "This was in conflict with my belief - confirmed in the holy scriptures - that we are all equal in the eyes of God," he says in his article.

I'm not a religious believer myself, but I don't in principle object to others holding religious beliefs. Everyone's experiences are different, and lead them to different conclusions. Reality really is in the eye of the beholder. Ideally, religious beliefs should uplift people, not just the believers themselves, but those around them as they find themselves treated with love and respect by believers.

In practice, however, religion too often takes a more destructive role -- squabbles over whose beliefs are "right" or "wrong" lead to hurt feelings between family members at best, and violence in the name of religion at worst; feelings of superiority over those who do not share our beliefs lead to treating our fellow human beings as something less than human; and systemic oppression of women is justified in the name of god.

"It is simply self-defeating for any community to discriminate against half its population. We need to challenge these self-serving and out-dated attitudes and practices - as we are seeing in Iran where women are at the forefront of the battle for democracy and freedom."

Carter and a group of eminent global leaders (including Nelson Mandela) have recently come out with a statement that declares: "The justification of discrimination against women and girls on grounds of religion or tradition, as if it were prescribed by a Higher Authority, is unacceptable." I applaud you, Jimmy Carter, for standing up for me and all women against religiously sanctioned oppression!

Too Expensive to Give Anything Away

I'm on business travel and currently staying in a super-swanky hotel, where the regular rate is $300+/night. At these rates, they evidently can't afford to provide you with complimentary internet (it's $9.95/day) or a complimentary breakfast.

Hotels like this are too expensive to provide you with any amenities. On the other hand, if I were staying at a more affordable hotel, such as one of the chain that rhymes with "Solid Gray Fin Text Press," all those amenities would be provided. And honestly, I don't think the bed would be any less comfortable or the rooms any louder.

Actually, this fancy schmancy hotel has paper-thin walls, through which I could hear my neighbor shouting obscenities and punching or hitting something, and then making a very loud grunting or groaning sound several times a minute for hours on end when I was trying to sleep. I called the front desk to report it, with the angle of being worried for his health, but of course they did nothing. I searched my bags and found some earplugs, which damped his noisy expressions enough that I was able to sleep. And I can currently hear somebody's alarm from down the hall -- it's been going for at least an hour (although luckily it's not close enough to really bother me).

You've Got to Be Kidding Me

As I watched this video, my jaw kept dropping to the floor and I kept having to pick it up and stick it back on my head.



Do people really think that way? (I guess the answer is "yes.")

Look, turd biscuits quoted in this video, let me explain a few things to you.

If the only arguments you have against Sonia Sotomayor are that she's a woman and a Latina, then you should hang up your hats and go home. Especially if you feel entitled to use sexist and racist language against her.

If she has made a ruling that you disagree with, then by all means, talk about that ruling and explain what's wrong with it. But if the only things you can think of saying about her are sexist swill like "let's hope she's not menstruating," then it's probably time to STFU.

I, for one, am tired of swimming in the collective pool that you have poisoned with your fear of teh wimminz and brown people. Get some counseling, take some medications, find Jesus for real instead of for pretend like the lot of you have* -- basically, whatever it takes -- and come back when you're able to speak civilly.


* Obviously I don't know the dude personally, but the last time I checked, Jesus never spoke about women and minorities like that.

Punk Rock OR

Anyone who's been reading this blog for any length of time knows that I am a serious geek. I love the math, computer science, and just about anything else seriously nerdy.

That's why I'm a huge fan of Laura McLay at Punk Rock Operations Research, a real-life professor of operations research at Virginia Commonwealth University. I think she and I may be twins separated at birth. Her blog has been in my feed reader for a couple of months, and I've been enjoying every article. My favorite one had to be the one about the convex hull of crepe recipes. I've often thought about the same sort of thing -- if you look at different cookbooks, you'll get different ingredient proportions in recipes for the same food. What kind of variation can you make in a recipe and still produce a good product?

Anyhow, I love Laura's blog and I encourage you all to check it out!

Happy Birthday, Rachel!

Just a shout-out to my sister Rachel, wishing her a happy birthday. Tomorrow is her birthday, but she's in Japan at the moment meaning that it's already the 9th over there.

Rachel and I share a single brain, which is in a jar in an undisclosed location. The nice thing about her being in Japan is that there's not much overlap in usage of our shared brain, since I'm sleeping while she's awake and vice versa.

She also is intent on ruining my life, but it's all good because I'm ruining hers right back at her.

Hope your day in Tsukuba is great, Rachie!

Adventures in Global Optimization (Part 1)

I realized that there hasn't been much in the way of math content here lately, so I decided I should talk some about global optimization, one of my favorite topics!

I've written about optimization before -- Pareto optimization and mixed-integer linear programming. Both of these are interesting topics: in Pareto optimization we're looking for the best solution to a problem with multiple objectives (e.g., a capitalistic health care system with conflicting objectives of maximizing profit and minimizing poor health); in (mixed-integer) linear programming we're finding the minimum of a function that is linear in all its variables, within a polytope of constraints.

I should start with some basic terms and concepts. Recall that finding the maximum of a function is equivalent to finding the minimum of the negative of that function, so without loss of generality, we can just talk about minimization. A minimum is the smallest value of the objective function, and a minimizer is the coordinates at which the minimum occurs.

A local minimizer is a point x where the objective function has a smaller value than it does at any point in the "neighborhood" of x. You know when you go to the store after a rain and there's one parking spot right near the front that's vacant because it's a big puddle? That point is a local minimizer of the parking lot. A global minimizer is a point x where the objective function has a smaller value than it does anywhere else in the domain.

Global optimization is the act of determining the global minimizer of an objective function. This sounds no different than what we do in linear programming, except in the case of linear programming, thanks to the fact that the objective function is linear, we know that the minimum we've found must be the global minimum.

There's another class of functions for which we can guarantee that the minimum we find is the global minimum: convex functions. Intuitively, a convex function is bowl shaped -- so if we just follow the slope of the function to the bottom of the bowl, we've found the global minimum. Formally, a convex function has the property that if you take two points on the convex function (let's call them x and y), the function always lies below the line between x and y, i.e., f(ax + (1-a)y) ≤ a f(x) + (1-a) f(y) for 0 ≤ a ≤ 1. For one-dimensional functions, this means that the second derivative is always non-negative, and equivalently, for multidimensional functions, the Hessian is positive semidefinite. The implication of this is that there's always a direction of descent that you can follow from any point (other than the minimizer) to find a point where the value of the objective function is smaller.

The trouble is, there are many objective functions we want to minimize that may not have such nice properties. There are lots of real-world objective functions that we know are not convex -- or even worse, we don't even know what they look like or how they behave.

There's a class of continuous functions known as coercive, with the property that for large |x| (magnitude x -- for a 2-D function, this would be (x²+y²)^1/2), the function approaches positive infinity. These functions look like a big bowl shape on a macroscopic scale, but up close they have some wiggles and wobbles. If a function is coercive, we know that it has to have at least one global minimizer. Intuitively, this is because the function has to be bounded from below, and you could find a bound that just touches the bottom of the function, which would touch right at the global minimizer(s). Unconstrained global optimization (that is, optimizing over the entire function space) is generally not possible if the objective function is not coercive.

But even if the function is coercive, there are no guarantees that we will find the global minimum. Indeed, without any other helpful properties, we can never be certain that we've found the global minimum!

Here's why. Suppose that you are given a "black box" function that you are told is coercive. As it turns out, whatever goes on inside the black box is controlled by your arch-enemy. You would never be able to find the global minimum of the function in a finite amount of time. The reason is because any optimization method that you would try would basically boil down to sampling the function at a bunch of points. Your nemesis would just keep moving the location of the "true global minimizer" to places that you hadn't yet sampled. The only way you would finally find it would be when you had exhausted every single point in the domain, which would take (literally) forever.

So if global optimization is such a hopeless business, what can we do? Well, many objective functions aren't as pathological as the inner workings of your worst enemy's mind, and the global minimum is findable. For the rest of them, we just settle for what we think is probably the global minimum. As for how we actually do the work of global optimization, this blog entry is long enough, and that will have to wait for next time.

Full Report

Vinny ended up enjoying the fireworks in practice.

The fireworks were scheduled to start at 10 pm. We staked out a good spot to view the fireworks at about 6:30 pm, and had a picnic. Jeff made some pulled beef barbecue and a fruit salad, and we had that along with some chips and some IBC root beer (which at one point, a cop mistook for actual beer and came over to make sure we weren't drinking alcohol).

After the picnic, I took Vinny to the playground for about an hour. We would have stayed longer, but he was really sleepy and started lying down on the crowded playground equipment, so I took him back before he got trampled. But that meant we still had about an hour and a half to kill before the fireworks started.

We managed to keep him entertained for that time, and he was excited when the fireworks began. Jeff had picked the absolutely perfect spot to sit -- the fireworks were literally launched right across the river from us. But the noise was a bit much for him and he started crying. But after I covered his ears with my hands, he was able to appreciate the fireworks and I heard a lot of "Wow!" and "Look at that fireworks!" coming out of him. By the end my arms were killing me, but it was worth it to give him that chance to enjoy the fireworks.

Question of the Day

Will Vinny enjoy fireworks in practice as much as he does in principle? Full report at 11.

Happy Three-Day Weekend!

I have today off for Independence Day, meaning that I have a nice three-day weekend before going back to work on Monday (and a gigantic center review on Tuesday).

Plans for the weekend include sleeping in (today I made it till 9!), enjoying my family, and taking Vinny to the fireworks. He really loves fireworks in principle, but we'll see if the noise scares him too badly.

Vinny's Videos

Vinny is a devotee of four main things on YouTube:

1. Fireworks (we'll see over the weekend whether he likes them up close and personal as much as he likes this video)
   


2. Wheels (he can't stop laughing when he watches this one)
   


3. Fans/Windmills (he calls this video "windmills with rooster")
   


4. The "Numa Numa" Guy (whom he calls "kid singing")