CMU老教授对Ph.D的理解
作者 lightsource | 2013-06-06 16:02 | 类型 学术园地, 海外学人, 行业动感 | Comments Off
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多年前看到的CMU教授写给自己学生的一篇关于如何读Ph.D的文章，甚是经典，特转来与诸位共勉。
USEFUL THINGS TO KNOW ABOUT PH.D. THESIS RESEARCH (Prepared for “What is Research” Immigration Course, 1. Introduction 1. Introduction - Ph.D. thesis is treated very seriously at leading universities. * Expectation is high. - Ph.D. thesis represents a substantial work. Faculty * Ph.D. thesis research is a task to ensure that the student * Through the Ph.D. thesis process the student is * Faculty are judged by the theses of their Ph.D. students. * High standard Ph.D. thesis is probably one of the most * Ph.D. thesis is probably the only real challenge for - Ph.D. qualifier is seldom a problem for motivated - Ph.D. thesis research is probably more mechanical than a new * Knowing this mechanism can be more important than thesis * Some information presented here may be relevant to your - This talk consists of pragmatic advice. * The talk is based on my personal experience (i.e., not - I happen to have research experience in both theory * This is a common sense talk and will have down to earth - “I wish someone told me this before.” 2. Why Ph.D. thesis could be really difficult for a student - Most likely this is your first, major research experience. * A big challenge for most students - No simple recipe * Different talents * Different kinds of theses * Different approaches - The work is judged by thesis committee (mostly advisor). This * Unlike other research you will do, the evaluation * No clear contract * No clear standard (we only know it is high) * Recall the Stanford murder case (the former student said, 3. Types of Ph.D. theses (from Allen Newell)–not a topic of this talk - Opens up new area - Provides unifying framework - Resolves long-standing question - Thoroughly explores an area - Contradicts existing knowledge - Experimentally validates theory - Produces an ambitious system - Provides empirical data - Derives superior algorithms - Develops new methodology - Develops a new tool - Produces a negative result 4. Growth of a star (the transformation process that some students go - Knowing everything stage * Student: “I have designed a supercomputer even before * Faculty: speechless - Totally beaten up stage * Student: speechless * Faculty: smiling at the student’s progress so - Confidence buildup stage * Student: “I am not stupid after all.” (student thinks) * Faculty: “Uh oh, she is ready to argue.” (faculty think) - Calling the shot stage * Faculty: “I am going to design an n-processor * Student: “You are crazy, because …” 5. Stages of Ph.D. thesis research a. Selection of area–not a topic of this talk b. Selection of advisor–not a topic of this talk c. Becoming a researcher in the area - Building up general knowledge, experience, and confidence - Knowing issues and important questions in the area - Capturing research opportunities * Don’t let any idea or question go by without first - Be alert and diligent. * Pay attention to new technologies - Examples * VLSI, networking, and new chips such as - Some useful things to do (from Dave Gifford, MIT) * Read recent proceedings of the best conferences, and * Keep a notebook that contains your research notes. * Follow references from one paper to another until d. Thesis proposal - It is the most crucial stage in the sense that the basic * To get important results you need to ask important * This is the time you need your advisor most. * Problems in later stages are usually rooted from a - Purpose * A research plan - A serious attempt to get an overview of the - Not really a contract * Need some flexibility because research * Forming the committee - Varies a lot - Choose people for your thesis committee that - However, there is usually no need to optimize - However it can be very important, when * you have a “questionable” advisor, or * you have an interdisciplinary topic. * A review - If there is any serious doubt, it had better - Proposal could sometimes be viewed as just a - Some of the difficult questions always asked in a thesis * What is your approach and what is new? * What is your secret weapon? (Herbert Simon) * How do you measure your own progress? * What are the success or completion criteria? * How will the expected results change the-state-of- - The grand challenge for a thesis proposal is to come up * It is easy to identify a general problem area, but - Need ideas * Just need one good idea, really * Unfortunately, there is no magic here * Need independent thinking - You should be good enough to start arguing with * Need to elaborate on focus, approach, experiment, - For theory research you may propose some new * Examples: area-time complexity (new VLSI - For system research you may design experiments * Examples: multiprocessor architecture, - Useful things to know when preparing a thesis proposal * Be honest. There is no need to exaggerate your * Pick a project that is manageable so you can do an * Include a tentative thesis outline and a month by - This may be difficult to do but it is better - This will also help gauge the total size of the e. Producing results - Lots of work–what else do you expect? * System–be inside an active project without losing - Need to be a worker as well as a conceptual - Your work depends on other people’s work and * Opportunity to see real problems * Getting good support, including - It seems that this arrangement really - Be quick, because you don’t want to be * Theory–be lucky! - Be flexible * It is hard to insist that you will prove a - Be quick, because theoretical results are - Keep the committee informed (at least those “trouble * You can get real help sometimes. * Committee members are obliged to talk to you. - Sometimes finding a qualified person beyond * Don’t want surprises in the later stage of the - Ways to finish a thesis * Incremental and adaptive approach - A sequence of incremental results * Big-bang approach (this is not recommended in - One big theorem - A big piece of software or hardware f. Writing - Why some students find that Ph.D. thesis writing is very * First major document * Writing is time-consuming–part of the .9999 - Fighting with fonts, figures, references, etc.? * Please don’t be too picky. * When results are not totally solid, writing can be - Can’t say too much and don’t want to say any - Writing about flaky results can be a real * In this case you should improve your * Writing has to do with presentation rather than - However, thesis writing is useful in the sense that it * Help get a large picture on what you really have. * Help organize the concepts * Completeness is forced. - You must take care of things that you have been * For example, you need to do comparison * Correctness of the results is checked. - You had better have the proof now for any * New insights on how things really work - New ways of looking at you results - Recommendations * Get some practice–write some papers before thesis - Write some joint papers with people who have * Need to know the theme of the thesis very well - Outline first - Write the conclusion first (try it at least) - Start writing chapters which are more settled. - Write the introduction last - Iterative process * Make the writing as precise as possible, so that you - Precise writing usually also yields good g. Getting final comments from the committee - Not too early or too late * Getting some committee members to read can be a - They are busy people. You want to give them an - How much to ask for comments varies a lot - Should not have any surprises now. * You had better know what you have been doing by now. * However, if there is any problem, it had better show h. Defense - Mostly a formality and a happy occasion (should be like * You know that your results are good and you will - You should know the answer to the question - * Getting a date set can be more difficult than you - Committee members do not necessarily stay at - Weekend defense is not really desirable. * May be difficult to get audience. - However defense is still very important: * Opportunity for final improvements for the thesis * Formal presentation to the community - Many people form their opinion of your n-years’ * Presentation material can be used for future - Used in recruiting presentations if you have * Psychologically important - Once in a life time occasion–you will remember * Don’t want to blow it. - Absolutely no surprises i. After defense - Usually there is still some minor work to be done for the * Defense was moved early for various reasons * New comments from defense * Did not have time or did not want to polish the - Publication * Articles, books (or give the thesis to your parents) * Very important to publish the results in journals - This is the only reliable way to archive your - Publication is important for academic career. - May break the thesis up in several articles. - Do it right away before you get on to the next * Books can be good too. - Follow-on work * Keep mining the thesis–why not? - Finally you are free! 6. “Methods” to get into the depth of a topic (or how to come up with - No magic, but we will still try …. - How to develop initial ideas * Study other work and do comparison - What are similar issues and solutions? * Look at examples - Generalization and abstraction * Make hypothesis and validate it formally or informally– * Do modeling and abstracting - Get the essence * Just do something–be active - Implementation–details reveal issues * Join a project to do some real work! * Handle a smaller case * Implement a throw-away simulator, language, - Start proving “theorems”, even if they are known to * Quick way to understand issues * Work with good, experienced researchers (don’t forget to - They might have deep insights on similar problems. - They can help calibrate the difficulty of the - You learn the subject matter from them more quickly - You learn their techniques * Every successful researcher has his or her own - Calculation, synthesis, analysis, - If they also get stuck once in a while, you know that - How to develop existing ideas further * Exploring problem and solution spaces - Enumerate parameters individually (and do quick * To see where your current ideas sit in the space - Correlate results - Generalize ideas and results to other points in the - Produce phenomena and explain them (Herb Simon) * Brainstorming your ideas with others * Presenting your ideas in papers or/and seminars - Ideas will be checked out carefully and * Example steps that can be used to get some depth from a - Explain the curve - Look at the problem and solutions spaces - Do some comparisons - Change the assumptions * How stable is the result? * How will results vary or correlate under - Derive some general principle * Similar curves for other situations? - General comments * Thinking is the key - Thinking is more important than reading * Books are not always right. - Note that in the system area with few - Be alert on all sorts of opportunities - Do the thinking right away while you have it. * Ideas and interest may be lost more quickly than * Talking to people - Don’t over do it (you still need to do the work 7. Breaking myths a. “Advisor is a stronger researcher than you.” - It is true that advisor is experienced, wise, smart - However, advisor is not always right. * Advisor is not as focussed as you. * Advisor does not have more time or energy than you * Advisor is not as innovative in general. - They know too much. - They are more conservative. * They know too many horror stories. - Aging does not help. * Advisor’s knowledge may be obsolete (don’t say this - You must believe that you can do better than advisor for b. “System theses take longer than theory theses.” - The most difficult part of a thesis is to come up with * Theory thesis is in general not about solving open - Actually good theoreticians always work on new * Greatest contributions are ground breaking * New approaches give new insights to old * For systems theses it is important that the major * Few theory students who finish really early are * Incompetent theory students are more noticeable than - There are some differences in systems and theory research * System needs implementation, whereas theory needs * Theory research is self-sufficient and system c. “Ph.D. thesis research follows some standard guidelines.” - Yes, a Ph.D. this must represent a substantial result in - But there are many ways to leave a mark in a research - There is a small percentage of Ph.D. theses completed in 8. Pitfalls to avoid (easy ones to avoid listed first) a. The goal is too big to reach. - Theory * Proving P /= NP * Proving P = NP is even worse (likely this thesis * Deciding whether P = or /= NP is best of the three - System * The initial effort is so large that real issues * It is important to size the project and evaluate the b. Ideas cannot stand without an implementation that competes - Chess machine implementation is OK, because there is no - In this sense, Warp hardware is more difficult than - Floating-point designs that require a high-performance - Never need to implement another vector processor! c. The thesis area is overtaken by technology and environment - Technology advances have solved the thesis problem. * A clever operating system using no more than 128K - Advisor (or student sometimes) has changed his or her - Other new projects have better approaches and - Other people have published similar and/or better - Advisor has a better job elsewhere or the project is - Lesson: You should always do your thesis as quickly as d. Totally isolated work - No encouragement and support–no one cares about your * Can’t even find an advisor sometimes * Doing a thesis away from CMU is really difficult. - System research * Lone ranger approach is almost suicidal. - No software, systems and application support - Very difficult to do anything real without - Theory research * At least global networking is needed. e. Not knowing when to stop - Thesis is not the last research you will do. - You can do the same research after your Ph.D. thesis - Learn to make reasonable assumptions to restrict the f. Unhealthy competition between student and advisor - This is more likely to happen in the theory area. - The potential is always there (especially for smart g. Lots of numbers and hacking but no fundamental principles - System research has to have more than implementation. - Implementation for a thesis research is interesting only - This problem should be fixed as early as possible. h. Things dragged on–wonderful general ideas in the beginning - Wrong areas for the student (and perhaps the advisor) - Nightmare case–it does no good to anyone. 9. Some other general advice - Stay away from areas that have been thoroughly mined by your * Keep yourself at the very front of a research area so that * After all in research what matters is the work that pushes * Make use new advances in other areas - Don’t avoid thinking * Thinking is hard but there is no substitute for it. - Psych yourself up for this unique experience of doing a Ph.D. * Make yourself believe you are solving the most important * Remember what worked for you before - If you work best when you are competing with others, * Must be very alert about issues and opportunities * Thesis process is sort of artificial (almost a torture in - The thesis is judged by a committee (mainly your * More subjective than exams - Probably one of the most humiliating experiences for - The process is not a typical research style–you * The thesis process can be long and treacherous. (Be - You don’t want depression. * There are quite a few very competent people who just do - Use forcing functions well to speed up the thesis process * Competing with someone else * Family pressure * Financial pressure * A job is waiting * Advisor is leaving or project is over * Equipment is retiring - Never throw away advisor’s comments * Cox-Denning case - Keep good relationship with your advisor (even after you * Good thing to do–no exception almost * Relationship is unique. - Advisor usually has lots of influence on you in this * Advisor may be your mentor for your entire career. 10. All the effort is worth it (believe it or not) - Experience from Ph.D. thesis research is unique. You have - Almost all leaders in research have this experience. You will - In summary, it is the best investment for becoming a successful | |
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