Coisas que é bom saber sobre a tese de doutorado

Esta é uma tradução livre da página USEFUL THINGS TO KNOW ABOUT PH.D. THESIS RESEARCH, de H.T. Kung (Computer Science Department, Carnegie Mellon University, 1987). Embora tenha sido escrito há muito tempo, a página continua bastante atual.

As observações do professor Kung são dirigidas aos condidatos a doutorado em Ciência da Computação, mas muitos dos conselhos aplicam-se igualmente bem aos doutorados em outras Ciências Exatas.

Presentation Outline 1. Introduction 2. Why Ph.D. thesis could be really difficult for a student 3. Types of Ph.D. theses (from Allen Newell)--not a topic of this talk 4. Growth of a star (the transformation process that some students go through to become a mature researcher)--which stage are you in? 5. Stages of Ph.D. thesis research 6. Methods to get into the depth of a topic (or how to come up with good ideas) 7. Breaking myths 8. Pitfalls to avoid (easy ones to avoid listed first) 9. Some other general advice 10. All the effort is worth it (believe it or not)

1. Introdução

A tese de doutorado é levada muito a sério nas grandes universidades:
- As expectativas são altas:
  - A tese de doutorado é um trabalho substancial. Professores muitas vezes dizem a outras pessoas que Nós temos um estudante de doutorado fazendo seu trabalho de tese nessa área. Surpreendentemente, isso é suficiente, muitas vezes, para convencer as pessoas de que o problema será, de alguma maneira, resolvido.
- A pesquisa de tese de doutorado deve garantir que o estudante pode, mais tarde, empreender trabalho de pesquisa de longo prazo de maneira independente e autônoma. (Se um estudante de doutorado não pretende ser um pesquisador, o trabalho de tese de doutorado não vale a pena, em geral.)
- O processo de doutorado transforma o estudante em um pesquisador profissional.
- Os professores orientadores são julgados pelas teses de seus alunos de doutorado.
- Oa altos padrões das teses de doutorado são provelmente o fator mais importante que contribui para o sucesso da pós-graduação nas grandes universidades [Americanas].
- A tese de doutorado é provavelmente a único desafio sério real para obter o grau de Doutor.
  - O exame de qualificação ao doutorado raramente é uma problema ou barreira para estudantes motivados.
A pesquisa de doutorado é provelmente mais mecânica do que um novo estudante de pós-graduação poderia pensar. (Mas é claro que o processo é complexo demais para ser automatizado.)
- Conhecer esse mecanimo pode ser mais importante que os resultados da tese propriamente ditos.
- Algumas das informações apresentadas aqui pode ser relevante para toda a sua carreira de pesquisador, ou seja, isso não é apenas para a sua tese de doutorado propriamente dita.
Esta palestra consiste de conselhos práticos:
- Esta palestra é baseada apenas na minha experiêmncia pessoal e não em pesquisa séria sobre o assunto. Eu tenho experiência de pesquisa nas duas áreas: teoria e sistemas. Nós vamos comparar o trabalho de pesquisa de tese nessas duas áres.
- Esta é uma palestra de senso comum e terá discussões básicas e práticas. Será to tipo Eu gostaria que alguém tivesse me contado essas coisas antes.

2. Por que um trabalho de tese de doutorado pode ser muito difícil para o estudante

Provavelmente esta é a seu primeira grande experiência de pesquisa.
- Um grande desafio para a maioria dos estudantes.
Não há uma receita simples a seguir.
- Talentos diferentes.
- Diferentes tipos de teses.
- Diferentes atitudes/pespectivas/maneiras de encarar.
O trabalho é julgado por uma banca/comitê (principalmente o orientador). Isso produz ansiedade.
- Diferentemente de outros trabalhos de pesquisa que você fará, o mecanismo de avaliação/julgamento de uma tese de doutorado é muito especial (tem características únicas).
- Não há um contrato claro (que rege o trabalho doutorado [cumpra as exigências do contrato e você recebá o título].
- Não há padrões claros (só sabemos que os padrões são altos, exigentes).
- Recall the Stanford murder case (the former student said, after he had finished--he did finish something-- his jail term, that he might do it again under a similar circumstance).

3. Tipos de teses de doutorado

(Esta lista é de Allen Newell.)

Abre uma nova área.
Propõe um arcabouço unificador [para uma área].
Resolve um problema que esteve em aberto há muito tempo.
Explora uma área de maniera meticulosa e completa.
Contradiz um conhecimento estabelecido.
Valida experimentalmente uma dada teoria.
Cria um sistema ambicioso.
Produz dados empríricos sobre um assunto.
Cria algoritmos melhores que os existentes.
Desenvolve uma nova metodologia.
Desenvolve uma nova ferramenta.
Produz um resultado negativo (ou seja, desmente uma conjectura ou suposição).

4. Nascimento de uma estrela

Alguns estudantes passam por um grande processo de transformação para se tornar um pesquisador. Em qual dos seguintes estágios você está?

Estágio eu sei tudo
- Estudante: Eu projetei um supercomputador antes mesmo de começar a pós-graduação.
- Professores: sem fala
Estágio estou derrotado e desanimado
- Estudante: sem fala (silêncio)
- Professores: Sorriso encorador diante do progresso do estudante. A comunicação agora é possível.
Estágio da aquisição de confiança
- Estudante (pensando): Eu não sou tão estúpido assim, afinal.
- Professores (pensando): Muito bem. Ele(a) está pronto(a) para conversar/discutir.
Estágio eu mando/domino
- Professores: Vou projetar um supercomputador com n processadores
- Estudante: Você está maluco, porque bla bla bla.

5. Estágios da pesquisa para uma tese de doutorado

[Kung está pensando no seguinte esquema: há uma proposta de tese, defendida perante uma banca, que depois acompanha o trabalho (que pode durar muitos meses) até a defesa final.]

Escolha de uma área (não é assunto desta palestra).
Escolha de um orientador (não é assunto desta palestra).
Tornando-se um pesquisador na área:
- Adquirindo conhecimento geral, experiência e confiança.
- Aprendendo quais são as questões e problemas importantes da área.
- Capturando oportunidades de pesquisa:
  - Não deixe escapar qualquer ideia ou pergunta sem antes examiná-la cuidadosamente. Esteja alerta e seja diligente.
  - Preste atenão às novas tecnologias. Exemplos: VLSI, redes, novos chips (como os chips Weitek para ponto flutuante há três anos que, num certo sentido, deram a motivação inicial para o projeto Warp).
Algumas coisas importantes a fazer (emprestado de Dave Gifford, MIT):
- Leia as atas (proceedings) recentes das melhores conferências e pergunte aos mais velhos e experientes quais foram os melhores artigos. Tente descobrir o que torna um artigo excelente (e portanto o que faz uma pesquisa excelente).
- Mantenha um caderno com suas anotações de pesquisa. Escreva todos os seus dados empríricos e suas ideias iniciais nesse caderno. Escreva anotações sobre o artigo que estiver lendo e reflita sobre as hipóteses do autor e a importância dos resultados.
- Siga os ponteiros que levam de um artigo a outro até que você conheça a área extremamente bem. Não conte com o seu orientador para que este abra uma gaveta do e lhe entregue todos os artigos relevantes. Eles não tem todos os artigos!
Proposta (projeto) de tese:
- Este é o estágio crucial mno sentido de que o conceito básico é estabelecido aqui.
  - Para obter resultados importantes, você precisa fazer perguntas importantes.
  - Este é momento em que você mais precisa do seu orientador.
  - Problemas/dificultades nos estágios posteriores usualmente têm origem numa proposta de tese fraca.
- Propósito/finalidade:
  - Um plano de pesquisa: - A serious attempt to get an overview of the whole research course - Not really a contract * Need some flexibility because research always has uncertainty.
  - Escolhendo a banca [Kung está pensando num esquema em que a banca é eswcolhida muito antes da defesa da tese e acompanha os estágios finai do trabalho do candidato]: - Varies a lot - Choose people for your thesis committee that can help with needed expertise. For example, it is useful to have a relevant theory faculty member on a systems committee and vice-versa. - However, there is usually no need to optimize too much on the selection of the committee members--advisor still plays the most important role. - However it can be very important, when * you have a "questionable" advisor, or * you have an interdisciplinary topic.
  - Um resumo: - If there is any serious doubt, it had better show up now. - Proposal could sometimes be viewed as just a forcing function for taking care of certain things.
- Algumas perguntas difíceis que são sempre levantadas numa proposta de tese:
  - Qual é o seu approach e o que há de novo?
  - Qual a sua arma secreta?
  - Como você mede o seu próprio progresso?
  - Quais são os critérios de successo e terminei? [Como você sabe se terminou o trabalho? Como você sabe que teve sucesso?]
  - Como os resultados esperados mudarão o estado da arte?
- O grande desafio de uma proposta de tese é inventar um approach ou um experimento.
  - É fácil identificar a área geral do problema, mas estabelecer o approach e planejar um experimento pode ser difícil. - Need ideas * Just need one good idea, really * Unfortunately, there is no magic here (however see some hints below). This is the hard part of any research project for everyone (not just for students).
  - Precisa de pensamento/matutar independente/autônomo. - You should be good enough to start arguing with your advisor on technical issues and research tastes.
  - Precisa detalhar o foco, o approach, o experimento e o impacto potencial/esperado do trabalho. - For theory research you may propose some new models of computation. * Examples: area-time complexity (new VLSI model in theory), parallel algorithms (new cost models) - For system research you may design experiments and argue their relevance. * Examples: multiprocessor architecture, compiler for a parallel machine
- Coisas úteis para se saber quando estiver preparando uma proposta de tese:
  - Seja honesto. Não é necessário exagerar suas afirmações (o anúncio do que você obteve)! Se você apontar para os os pontos fracos do seu approach você desarmará os críticos.
  - Escolha um projeto que seja administrável (não excessivamente ambicioso) de modo que você possa fazer um trabalho excelente — as coisas são sempre mais difíceis do que elesd parecem no início. É bem melhor fazer um trabalho excelente em um projeto de tamanho modesto que um trabalho modesto em um projeto enorme.
  - Inclua na sua proposta de tese um sumário tentativo da tese e um calendário mês-a-mês das várias etapas do trabalho. - This may be difficult to do but it is better than no plan at all. - This will also help gauge the total size of the work you are committing yourself to do.
Produzindo resultados - Lots of work--what else do you expect? * System--be inside an active project without losing sight of thesis - Need to be a worker as well as a conceptual person. - Your work depends on other people's work and vice versa * Opportunity to see real problems * Getting good support, including encouragement and demand, from the group - It seems that this arrangement really works in all cases. - Be quick, because you don't want to be overtaken by the environment (this is one of the pitfalls to avoid, as described below) * Theory--be lucky! - Be flexible * It is hard to insist that you will prove a theorem before you go to sleep. - Be quick, because theoretical results are totally portable and so competition can be keen. - Keep the committee informed (at least those "trouble makers") * You can get real help sometimes. * Committee members are obliged to talk to you. - Sometimes finding a qualified person beyond your advisor to discuss your work can be difficult. * Don't want surprises in the later stage of the thesis - Ways to finish a thesis * Incremental and adaptive approach - A sequence of incremental results * Big-bang approach (this is not recommended in general) - One big theorem - A big piece of software or hardware
Escrevendo
- - Why some students find that Ph.D. thesis writing is very difficult * First major document * Writing is time-consuming--part of the .9999 perspiration (Satya) - Think how many good sentences you can write in an hour. - Fighting with fonts, figures, references, etc.? * Please don't be too picky. * When results are not totally solid, writing can be really difficult even for an experienced writer (now you know another reason why proposal writing is not easy) - Can't say too much and don't want to say any less - Writing about flaky results can be a real challenge. * In this case you should improve your results first. * Writing has to do with presentation rather than finding new results. So writing may not be as exciting.. - However, thesis writing is useful in the sense that it helps reveal possible problem areas and provides new insights. * 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 ignoring. * For example, you need to do comparison with other results * Correctness of the results is checked. - You had better have the proof now for any plausible "theorem" that you have been believing. * 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 substantial writing experience * 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 know exactly what you are talking about. This will save lots of rewriting. - Precise writing usually also yields good English.
Obtendo os comentários finais da banca/comitê
- - Not too early or too late * Getting some committee members to read can be a challenge. - They are busy people. You want to give them an "optimal" version to make comments.
- - 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 up now.
Defesa
- - Mostly a formality and a happy occasion (should be like that) * You know that your results are good and you will present them well. - You should know the answer to the question - "What are the three main ideas in your thesis?". You should be able to rattle them off and relate them to previous work. * Getting a date set can be more difficult than you think. - Committee members do not necessarily stay at CMU as long as you do! - 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' work from this presentation * Presentation material can be used for future presentations - Used in recruiting presentations if you have not settled on a job yet * Psychologically important - Once in a life time occasion--you will remember it always. * Don't want to blow it. - Absolutely no surprises i. After defense - Usually there is still some minor work to be done for the thesis (too bad) * Defense was moved early for various reasons * New comments from defense * Did not have time or did not want to polish the thesis before defense - 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 results. (You don't want to lose them after all these efforts, do you?) - Publication is important for academic career. - May break the thesis up in several articles. When appropriate, some articles may have joint authors such as your advisor. - Do it right away before you get on to the next thing. * 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 good ideas)

- 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-- keep trying - You will discover issues at least. * 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, design, etc. - Start proving "theorems", even if they are known to be difficult. * Quick way to understand issues * Work with good, experienced researchers (don't forget to use your advisor!) - They might have deep insights on similar problems. - They can help calibrate the difficulty of the problem. - You learn the subject matter from them more quickly and directly. - You learn their techniques * Every successful researcher has his or her own bag of "tools": - Calculation, synthesis, analysis, persistence - If they also get stuck once in a while, you know that you are not that bad after all. - How to develop existing ideas further * Exploring problem and solution spaces - Enumerate parameters individually (and do quick pruning) * To see where your current ideas sit in the space - Correlate results - Generalize ideas and results to other points in the space - 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 systematically (see above on thesis writing) * Example steps that can be used to get some depth from a simple result such as a speed-up curve - 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 different assumptions? - 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 exceptions people who build systems do not have time nor need to write up their experience--it is too bad but it is a reality. - 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 you like to believe * Talking to people - Don't over do it (you still need to do the work yourself)

7. Quebrando alguns mitos

a. "Advisor is a stronger researcher than you." - It is true that advisor is experienced, wise, smart (maybe), and knowledgeable in general. Advisor also sees a bigger picture, and has contacts in the area. - However, advisor is not always right. * Advisor is not as focussed as you. * Advisor does not have more time or energy than you do. * 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 in front of him or her!). - You must believe that you can do better than advisor for some research areas. b. "System theses take longer than theory theses." - The most difficult part of a thesis is to come up with some good, new ideas. The difficulty in getting new ideas is the same for theory or system research. * Theory thesis is in general not about solving open problems. - Actually good theoreticians always work on new problems, models and methods so that they can solve the problems that are "solvable" in the first place. * Greatest contributions are ground breaking ones, such as new models. * New approaches give new insights to old problems. This is the way open problems usually get solved (e.g., the four-color problem). * For systems theses it is important that the major ideas in the thesis are independent of the implementation--the goal is to have the ideas live on in other systems as well. A good systems thesis usually has a new algorithm or new method at its core. * Few theory students who finish really early are likely those who have prior research experience. (Recall that theory results are highly portable!) * Incompetent theory students are more noticeable than weak system students. So we don't often see theory students who drag on for a long time. - There are some differences in systems and theory research however, but they should not have too much impact on the thesis research time. * System needs implementation, whereas theory needs more background study. * Theory research is self-sufficient and system implementation may depend on other people's work (you should not get into a situation where you don't have control). c. "Ph.D. thesis research follows some standard guidelines." - Yes, a Ph.D. this must represent a substantial result in a very high standard. - But there are many ways to leave a mark in a research area. As long as you have come up with some good ideas and pushed the frontier of knowledge, you will be surprised sometimes how flexible your committee could be in terms of the research approach, acceptable results, and thesis presentation. - There is a small percentage of Ph.D. theses completed in unusual manner. Don't give up too early if you belong to this class. Try it or you will never know.

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 will never finish!). * Deciding whether P = or /= NP is best of the three (i.e., be flexible) - System * The initial effort is so large that real issues never get a chance to be looked at. * It is important to size the project and evaluate the total effort carefully based on past experiences. b. Ideas cannot stand without an implementation that competes with commercial products. - Chess machine implementation is OK, because there is no commercial competitor. - In this sense, Warp hardware is more difficult than software. - Floating-point designs that require a high-performance chip implementation to validate the concept would be disastrous. - 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 memory is not very interesting today. - Advisor (or student sometimes) has changed his or her interest - Other new projects have better approaches and opportunities - Other people have published similar and/or better results. - Advisor has a better job elsewhere or the project is over. - Lesson: You should always do your thesis as quickly as possible. d. Totally isolated work - No encouragement and support--no one cares about your thesis * 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 for evaluation - Very difficult to do anything real without feedback from a community - 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 (while making more money). - Learn to make reasonable assumptions to restrict the problem 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 professors with lots of ego). In general if both sides try to be fair, things can always be worked out. 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 if it can be used to validate some theory. - This problem should be fixed as early as possible. h. Things dragged on--wonderful general ideas in the beginning that never get developed into a coherent approach (i.e., heading to a black hole--there is no output) - Wrong areas for the student (and perhaps the advisor) with respect to ability and interest - Nightmare case--it does no good to anyone.

9. Some other general advice

- Stay away from areas that have been thoroughly mined by your ancestors. * Keep yourself at the very front of a research area so that you have a better chance to hit something big or at least new. * After all in research what matters is the work that pushes us into new territories. * 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. thesis * Make yourself believe you are solving the most important problem in the world * Remember what worked for you before - If you work best when you are competing with others, then create some confrontation. * Must be very alert about issues and opportunities * Thesis process is sort of artificial (almost a torture in some way) - The thesis is judged by a committee (mainly your advisor) * More subjective than exams - Probably one of the most humiliating experiences for people of this age (advisors should all remember this and be considerate.) - The process is not a typical research style--you don't do anything similar to it again even if you will be doing research after the degree. * The thesis process can be long and treacherous. (Be prepared for it.) - You don't want depression. * There are quite a few very competent people who just do not want to go through this. - 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 graduate) * Good thing to do--no exception almost * Relationship is unique. - Advisor usually has lots of influence on you in this very important stage of your life. Advisor also appreciates the good research you did with him, and is in general interested in your well-being. * Advisor may be your mentor for your entire career.

10. O esforço vale a pena (acredite ou não)

A experiência de uma tese de doutorado é algo único. Você aprende como se faz pesquisa. Seu trabalho de pesquisa futuro será mais interessante porque você já saberá como fazê-lo, e assim terá mais liberdade e poderá se divertir mais.

Quase todos os lideres em pesquisa passaram por essa experiência. Você terá confiança na sua habilidade de pesquisa. Você verá as coisas de maneira diferente da das pessoas que não passaram pelo processo. O trabalho de tese de doutorado continua sendo a melhor maneira que conhecemos para criar pesquisadores poderosos.

Em resumo, o doutorado é o melhor investimento para se tornar um pesuqisador bem sucedido.