Computers have beaten human world champions at chess and, earlier this year, the board game Go. So far, though, they have struggled at the card table. So we challenged one AI to a game.

    Why is poker(扑克) so difficult? Chess and Go are “information complete” games where all players can see all the relevant information. In poker, other players' cards are hidden, making it an “information incomplete” game. Players have to guess opponents' hands from their actions—tricky for computers. Poker has become a new benchmark for AI research. Solving poker could lead to many breakthroughs, from cyber security to driverless cars.

    Scientists believe it is only a matter of time before AI once again vanquishes humans, hence our human-machine match comes up in a game of Texas Hold's Em Limit Poker. The AI was developed by Johannes Heinrich, researcher studying machine learning at UCL. It combines two techniques: neural(神经的) networks and reinforcement learning(强化学习).

    Neural networks, to some degree, copy the structure of human brains: their processors are highly interconnected and work at the same time to solve problems. They are good at spotting patterns in huge amounts of data. Reinforcement learning is when a machine, given a task, carries it out, learning from mistakes it makes. In this case, it means playing poker against itself billions of times to get better.

    Mr Heinrich told Sky News: “Today we are presenting a new procedure that has learned in a different way, more similar to how humans learn. In particular, it is able to learn abstract patterns, represented by its neural network, which allow it to deal with new and unseen situations.”

    After two hours of quite defensive play, from the computer at least, we called it a draw.

    As a young boy, I sometimes traveled the country roads with my dad. He was a rural mill carrier, and on Saturdays he would ask me to go with him. Driving through the countryside was always an adventure: There were animals to see, people to visit, and chocolate cookies if you knew where to stop, and Dad did.

    In the spring, Dad delivered boxes full of baby chickens, and when 1 was a boy it was such a fun to stick your finger 'through one of the holes of the boxes and let the baby birds peck on your fingers.

    On Dad' s final day of work, it took him well into the evening to complete his rounds because at least one member from each family was waiting at their mailbox to thank him for his friendship and his years of service. "Two hundred and nineteen mailboxes on my route." he used to say, "and a story at every one. " One lady had no mailbox, so Dad took the mail in to her every day because she was nearly blind. Once inside, he read her mail and helped her pay her bills.

Mailboxes were sometimes used for things other than mail. One note left in a mailbox read. "Nat, take these eggs to Marian; she's baking a cake and doesn't have any eggs. " Mailboxes might be buried in the snow, or broken, or lying on the groom:. bat the mail was always delivered On cold days Dad might find one of his customers waiting for him with a cup of hot chocolate. A young wrote letters but had no stamps, so she left a few button on the envelope in the mailbox; Dad paid for the stamps. One businessman used to leave large amounts of cash in his mailbox for Dad to take to the bank. Once, the amount came to 8 32,000.

    A dozen years ago, when I traveled back to my hometown on the sad occasion of Dad's death,  the mailboxes along the way reminded me of some of his stories. I thought I knew them all, but that wasn't the case.

    As I drove home, I noticed two lamp poles, one on each side of the street. When my dad was around, those poles supported wooden boxes about four feet off the ground. One box was painted green and the other was red, and each had a long narrow hole at the top with white lettering: SANTA CLAUS, NORTH POLE. For years children had dropped letters to Santa through those holes.

    I made a turn at the comer and drove past the post office and across the railroad tracks to our house. Mom and I were sitting at the kitchen table when I heard footsteps. There, at the door, stood Frank Townsend, Dad's postmaster and great friend for many years. So we all sat down at the table and began to tell stories.

    At one point Frank looked at me with tears in his eyes. " What are we going to do about the letters this Christmas?" he asked.

    "The letters?"

    'I guess you never knew. "

    "Knew what?"

    " Remember, when you were a kid and you used to put your letters to Santa in those green and red boxes on Main Street? It was your dad who answered all those letters every year. "

    I just sat there with tears in my eyes. It wasn't hard for me to imagine Dad sitting at the old table in our basement reading those letters and answering each one. I have since spoken with several of the people who received Christmas letters during their childhood, and they told me how amazed they were that Santa had known so much about their homes and families.

For me, just knowing that story about my father was the gift of a lifetime.

    Everything was put neatly into my suitcase．I'm a flight attendant．I'm so organized，my half of the closet could be a display at The Container Store．My husband's half of the closet？Just thinking about it made my head ache．I carried my suitcase downstairs．Bill was in the kitchen cooking．Looking at the messy kitchen，I shouted，“Why do you have to be so messy？” Bill looked hurt，“What？” I sighed and left for the airport．

    On my last flight，an elderly couple had the seats in my section．They held hands during takeoff．Later I caught them looking into each other's eyes．Something about that look was familiar．Then I realized：it was the look Bill and I had worn in our wedding photographs．I couldn't resist asking them about the secret of their long-lasting marriage. “Have fun together，”the man said, “and never take each other for granted．”

    His words circled in my head long after we landed．Bill wasn't perfect．But then，was I？I kept complaining about his messiness and forgot his kindness，his ability to see the bright side of every situation-qualities that ran so much deeper，the reasons I had married him in the first place

    I took out my cell phone and called Bill. “I miss you already.” I said．“I miss you too，Kim，” he said．As soon as my flights were over，I rushed home．Bill met me at the door．"I have a surprise for you．"he said and led me into the kitchen．I glanced around the room．He really had worked hard．In spite of the fingerprints on that microwave floor，I could see our reflection in it：my husband and I，our smiles glowing with love for each other，just like in our wedding photos．

    When I was growing up，I was embarrassed to be seen with my father. He was badly crippled (跛脚)，and when we would walk together，his hand on my arm for balance，people would stare，I would be ashamed of the unwanted attention.

    It was difficult to walk together—and because of that，we didn't say much as we went along. But as we started out，he always said，“You set the pace. I will try to follow you.”

    Our usual walk was to or from the subway，which was how he got to work. He went to work sick，and even in bad weather. He almost never missed a day，and would make it to the office even if others could not. It was a matter of pride for him.

    When snow or ice was on the ground，it was impossible for him to walk，even with help. At such times my sister or I would pull him through the streets of Brooklyn，N.Y.，on a child's sleigh to the subway entrance. Once there，he would try to grasp handrail until he reached the lower steps that the warmer tunnel air kept ice free. In Manhattan the subway station was the basement of his office building，and he would not have to go outside again until we met him in Brooklyn on his way home.

    When I think of it now，I am surprised at how much courage it must have taken for a grown man to suffer from shame and disability. And I am also surprised at how he did it—without bitterness or complaint.

    He never talked about himself as an object of pity，nor did he show any envy of the more fortunate or able. What he looked for in others was a “good heart”，and if he found one，the owner was good enough for him.

    Now that I am older，I believe that is a proper standard by which to judge people，even though I still don't know exactly what a “good heart” is. But I know the times I don't have one myself.

    He has been away for many years now，but I think of him often. I wonder if he sensed my reluctance to be seen with him during our walks. If he did，I am sorry I never told him how sorry I was，how unworthy I was，how I regretted it. I think of him when I complain about my troubles，when I am envious of another's good fortune，when I don't have a “good heart”．

    Mary Krupa became friends with the grey squirrels during her first week at Penn State,after spotting them running around and idly（漫不经地）wondering what they would look like with tiny hats on their heads.Today, everyone at the university knows her as the "Squirrel Girl".

    Mary started bringing them food,and gradually they began to trust her.She managed to put a hat on a squirrel and take a picture.Thinking that her colleagues could do with something to lift up their spirits,she started posting similar Photos on Facebook.The response Was greatly positive,and before long Mary and her squirrels became an Internet sensation.

    Growing up in a neighborhood outside State College,Mary was always fond of birds and animals around her home,but she didn't interact with people very much.She was later diagnosed with Asperger's syndrome,but the squirrels changed that.The squirrels are actually a good way to break the ice,because I'll be sitting here patting a squirrel and other people will come over and well just start like feeding the squirrels together and chatting about them,"she said."I am a lot more outgoing.

    And in case you're wondering how Mary is able to get the squirrels to do what she wants for her photos,it has a lot to do with food.For example,whenever she wants them to hold or play with something,she puts peanut butter on the prop（道具）,and they'll grab it.But getting to that part took a while.In the beginning,she would throw peanuts up the trees on campus and invite the squirrels to come down and get them,but they hesitated to approach her.She had the patience to earn their trust,though.

    This year,Mary is graduating with a degree in English and wildlife sciences.She wants to be a science writer and educate people on how to preserve the environment.As for her furry friends,Mary plans to stay in the area and visit them as often as she can.

    “Why do I live? Why do I wish for anything, or do anything? Is there anything in my life that will not be destroyed by my death?”

    These are the words of the famous Russian writer Leo Tolstoy. Like Tolstoy, many people ask these difficult questions. And they struggle to find meaning in their life. Tolstoy spent his whole life trying to answer difficult questions like these. His search for answers influenced his writing.

    On August 28th, 1828, Leo Tolstoy was born in the country of Russia.

    As a child, Tolstoy was a member of the Russian Catholic Church. But as a young man, he began to question that faith. Tolstoy wanted to make his own moral decisions; he was tired of being told what to believe. He thought people could achieve a degree of perfection if they tried hard enough. So he worked very hard at being the best in everything he did. He thought that he would find meaning and truth in success.

    In the 1850s, Leo Tolstoy wrote his first stories. He wrote about his experiences in the army He also told stories about when he was a child. These works were published and Tolstoy became a well-known writer.

    Tolstoy was finally successful. He earned the respect he always wanted. Many wealthy and intelligent men met and talked with Tolstoy. Some of the men were writers like him. They talked a lot about faith and the meaning of life. But soon Tolstoy recognized that these men were not perfect. Now he knew they could not answer his questions about faith.

    So in the 1860s, Tolstoy tried a different way to find meaning. He opened a school for the children of his serfs -the people who worked on his land. These workers were very poor. He wanted to help them because he thought they were more honest than the wealthy people he knew.

    Tolstoy learned many things from his workers. He respected how they worked hard to provide for their families. He began to believe that marriage and family would give his life meaning. So in 1862, Leo Tolstoy married a young woman named Sonya Behrs.

    The next 15 years were the best years of Tolstoy's life. It was during this time that he wrote his most famous books -War and Peace and Anna Karenina. Many literature experts say that War and Peace is one of the greatest books ever written.

    Both War and Peace and Anna Karenina communicate Tolstoy's beliefs about the Russian nation, church and people. They also communicate what he thought was the answer to all his questions. Tolstoy believed humans were supposed to live a simple lite and take care of their families. Tolstoy thought this would satisfy him and bring him happiness.

    Leo Tolstoy is still a very respected writer today. His faith and writings have influenced many people. Tolstoy's search for the meaning of life is something everyone can understand. His teachings still interest people all over the world.