Multi-armed bandit (MAB) algorithms could be used to select a subset of the k most informative summary statistics, from a pool of m possible summary statistics, by reformulating the subset selection problem as a MAB problem. This is suggested by experiments that tested five MAB algorithms (Direct, Halving, SAR, OCBA-m, and Racing) on the reformulated problem and comparing the results to two established subset selection algorithms (Minimizing Entropy and Approximate Sufficiency). The MAB algorithms yielded errors at par with the established methods, but in only a fraction of the time. Establishing MAB algorithms as a new standard for summary statistics subset selection could therefore save numerous scientists substantial amounts of time when selecting summary statistics for approximate bayesian computation.

自第七屆起立法委員減半為113席次，任期由3年改為4年，立法院已真正成為我國「單一國會」。隨之立法院的功能也就跟著大幅提升，所選出來的立法委員除了更具民意基礎之外，也得以充分反映民意和選民利益，同時隨著立法委員全面改選和席次增加後，除了依法編制的公務單位及行政人員襄助立法委員行使職權外，立法委員個人所聘用的公費助理人數較過去大幅提升，其能發揮的功能性，直接影響每一位委員的問政表現。 由於國會助理的聘期為一年一聘制，與立法委員同進退，因此，在非自願性離職的情況下，立法委員未連任或不再參選而離職的國會助理不在少數，另外也有因政治理念不合，或另覓更好的工作環境條件而自願離職的也佔大多數。然而第七屆立委減半後，直接衝擊最大的是近兩千名國會助理，面臨非自願性離職的失業潮，因此立法委員是否繼續連任，更是主要攸關助理們去留的命運。 本研究的主要動機，乃在於探討離職後的國會助理，在失去政治權力的環境下，應如何未雨綢繆做好生涯規劃？進而從非自願性失業的現象，深入探究國會助理制度的缺失。離職後的國會助理，從事哪方面的行業較容易得心應手？以及曾擔任國會助理工作的資歷，對轉業到底有多少的助益？將加以深入探討。 本研究目的主要是探討國會助理面對非自願性失業後，未來生涯規劃之情況；以及分析在失去國會權力光環的政治環境下，國會助理轉業後對目前的工作滿意；爾後根據研究結果，提供國會助理轉換跑道時之建議和參考。 本研究採質化研究之深度訪談法，總計訪談12位因委員未能順利連任當選第七屆立法委員，以致於非自願性失業的國會助理。經本研究結果發現如下： 一、雖有流動、不出委員範疇：第四屆至第六屆立委席次擴增為225席後，國會助理們會因為立委席次的增加，有多方面選擇委員辦公室的就業機會，因此助理流動率雖高，卻仍然始終在委員與委員辦公室之間流竄。 二、不適應者、回歸助理者眾：甚至有部分助理轉換至其他產業界後，在不能適應外界工作環境下，重返立法院繼續擔任國會助理工作的不在其數。 三、缺乏配套、助理權益難保：如今第七屆立委減半後，委員辦公室的選擇性減少，且由於委員辦公室助理流動率低，再加上立法院遲遲未能針對國會助理制度，訂定一套完整的配套措施，來保障國會助理應有的權益。 四、優勢蛻減、選擇不再戀棧：反觀之，在產官學界的工作條件（如：薪資、升遷、福利、教育訓練）優於國會助理的情況下，即使立委減半後，在僧多粥少的環境下，對於未來國會助理的評價與發展，仍抱持著悲觀的態度，助理們紛紛選擇不再戀棧立法院。 本研究根據研究發現，提出以下五點建議： 一、由於大多數國會助理認為此份工作並非長治久安，對於未來的生涯規劃，仍是需要按部就班的計畫。 二、卸任的立委諸公們，通常在自身難保的情況下，未能有計畫安排助理的出路，助理們只能自求多福，積極尋找適合何自己的下一個伯樂。 三、國會助理的行業雖不具有保障性，但在無形中所創造出自我的附加價值，將使其資歷在轉換其他行業時成為很大的助益。 四、國會助理所負責的工作內容複雜且繁瑣，可藉由工作接觸累積人脈，建立個人的人際關係。 五、未來可朝向「國會助理專業證照制度」發展，爾後再制定國會助理法治化之相關法令，來保障國會助理的權益，以提升立法委員問政。 / Legislative seats for the 7th Legislative Yuan were halved to 113 and the term was extended from original 3 to 4 years. The Legislative Yuan has ever since been the “Unicameralism”. As the congress is empowered in functions, the members of the Legislative Yuan will fully reflect the public’s opinions and voters’ interests. After the re-election and the increase in seats, aside from receiving help from the public service units and staff, the legislators also receive assistance from the increased numbers of publicly funded assistants. The function of those assistants will directly impact on the performance of the legislators. The term of assistants lasts one-year, and they lose their jobs if the legislators lose the re-election. The assistants who leave also include those whose legislators did not get re-elected or they themselves no longer are candidates of legislators, this leads to the fact that many assistants involuntarily leave their jobs. Those leave voluntarily might be because of the different political ideas or they seek for a better working environment. But the tremendous impact came from the unemployment of those nearly 2000 assistants who lost their jobs non-voluntarily after the 7th Legislative Yuan. The main motive of this study was to explore how those assistants plan for their lives after leaving current job. And from the phenomenon of involuntary unemployment, the study focused on the shortcoming of the congressional assistant system. It explored which industry was easier for assistants who left their jobs to enter, and how their career as an assistant can be useful for their next job. The main purpose of this study was to explore how the assistants plan for their lives after leaving the job involuntarily. It also analyzed the job satisfaction of the ex-assistants after leaving the congress. The research provided some suggestions and advices for the assistants who change track in their career. This study adopted the qualitative, in-depth interviews, in total 12 assistants were interviewed, who left their job involuntarily. The findings of this study are as follows: 1. The increase in seats to 225 provided more job opportunities for the assistants, though the turnover rate was high, the assistant still worked in one of the offices in the congress. 2. There are many ex-assistants who could not adapt to the external environment returned to the congress. 3. The reduction of members of congress and the low turnover rate in the office after the 7th Legislative Yuan requires a supporting measure to protect the rights of assistants. 4. The external working conditions were better than the environments in congress. There were many assistants who chose not to stay in the Legislative Yuan. For example, in joining the academic, governmental or industrial community, the salary, benefits, promotion and training are better than what is offered in Legislative Yuan. Based on the research finding, the following five recommendations were proposed: 1. Since most assistants consider their current job is not a long-term career, they should plan their life in a more careful, step by step manner. 2. The non-incumbent legislators usually do not have a plan for the assistants while their own jobs are at risk. And assistants need to search for the next job by themselves. 3. The intangible added value of being assistants while they worked in the congress will help ex-assistants to adapt their next job. 4. The assistants’ job description includes being responsible for complex and tedious works, which will help them to develop personal relationships and connections. 5. In the future, the “Assistant Professional Certification” should be established. Relevant laws concerning the assistants should be passed to protect the rights of the assistants and to enhance quality of policy decisions made by the legislators.

Cryptographic hash functions are an important tool in cryptography to achieve certain security goals such as authenticity, digital signatures, digital time stamping, and entity authentication. They are also strongly related to other important cryptographic tools such as block ciphers and pseudorandom functions. The standard and widely used hash functions such as MD5 and SHA-1 follow the design principle of Merkle-Damgard iterated hash function construction which was presented independently by Ivan Damgard and Ralph Merkle at Crypto'89. It has been established that neither these hash functions nor the Merkle-Damgard construction itself meet certain security requirements. This thesis aims to study the attacks on this popular construction and propose schemes that offer more resistance against these attacks as well as investigating alternative approaches to the Merkle-Damgard style of designing hash functions. This thesis aims at analysing the security of the standard hash function Cellular Authentication and Voice Encryption Algorithm (CAVE) used for authentication and key-derivation in the second generation (2G) North American IS-41 mobile phone system. In addition, this thesis studies the analysis issues of message authentication codes (MACs) designed using hash functions. With the aim to propose some efficient and secure MAC schemes based on hash functions. This thesis works on three aspects of hash functions: design, cryptanalysis and applications with the following significant contributions: * Proposes a family of variants to the Damgard-Merkle construction called 3CG for better protection against specific and generic attacks. Analysis of the linear variant of 3CG called 3C is presented including its resistance to some of the known attacks on hash functions. * Improves the known cryptanalytical techniques to attack 3C and some other similar designs including a linear variant of GOST, a Russian standard hash function. * Proposes a completely novel approach called Iterated Halving, alternative to the standard block iterated hash function construction. * Analyses provably secure HMAC and NMAC message authentication codes (MACs) based on weaker assumptions than stated in their proofs of security. Proposes an efficient variant for NMAC called NMAC-1 to authenticate short messages. Proposes a variant for NMAC called M-NMAC which offers better protection against the complete key-recovery attacks than NMAC. As well it is shown that M-NMAC with hash functions also resists side-channel attacks against which HMAC and NMAC are vulnerable. Proposes a new MAC scheme called O-NMAC based on hash functions using just one secret key. * Improves the open cryptanalysis of the CAVE algorithm. * Analyses the security and legal implications of the latest collision attacks on the widely used MD5 and SHA-1 hash functions.

La compréhension de la dynamique des réarrangements génomiques est importante en phylogénie. La phylogénie est l'étude de l'évolution des espèces. Un but majeur est d'établir les relations d'évolution au sein d'un groupe d'espèces, pour déterminer la topologie de l'arbre d'évolution formé par ce groupe et des ancêtres communs à certains sous-ensembles. Pour ce faire, il est naturellement très utile de disposer d'un moyen d'évaluer les distances évolutionnaires relatives entre des espèces, ou encore d'être capable d'inférer à un groupe d'espèces le génome d'un ancêtre commun à celles-ci. Ce travail de thèse, dans la lignée d'autres travaux, consiste à élaborer de tels moyens, ici dans des cas particuliers où les génomes possèdent des gènes en multiples copies, ce qui complique les choses. Plusieurs hypotèses explicatives de la présence de duplications ont été considérées, des formules de distance ainsi que des algorithmes de calcul de scénarios ont été élaborés, accompagnés de preuves de complexité.