怎样由遍历序列确定二叉树

在文 [1 ]至文 [4]中都介绍了遍历一棵二叉树的三种方法 :先序遍历、中序遍历和后序遍历 .每棵二叉树的先序遍历序列、中序遍历序列和后序遍历序列都是唯一的 .但是不同的二叉树的先序遍历序列或中序遍历序列或后序遍历序列有可能是相同的 .就如我们已知一个关系要求能求出它的关系矩阵 ,已知一个关系的关系矩阵也能求出关系矩阵所表示的关系一样 ,要求我们不但能从二叉树求它的遍序序列 ,而且能从二叉树的遍历序列求出它们所表示的二叉树 .在文 [1 ]中只指出 :给定结点的先序序列和中序序列可唯一确定一棵二叉树 .但文 [1 ]没有给出证明 .本文指出了由后序遍历序列和中序遍历序列也可唯一确定一棵二叉树 ,并给出了相应的证明     

EFL teachers’ perceptions of English language policy at the elementary level in Taiwan

Due in large part to the trends towards economic globalization, English has become the most widely disseminated and ubiquitous international language. The purpose of the study was to investigate what Taiwan’s EFL teachers at the elementary level believe about the policy of English as a compulsory subject and how they perceive the benefits and obstacles of the policy’s implementation. Ten elementary English teachers in Tainan City and its suburban areas participated in this study. Data were collected through teachers’ interviews, classroom observation and document analysis. Results found that all ten teachers agreed with the policy for English as a compulsory subject at the elementary level. They observed both positive and negative sides of this top‐down policy. Classroom observation and interview data revealed that EFL teachers had to plan their English classes with the constraints on a large class of students with mixed levels of proficiency, limited teaching hours and resources. Parents’ expectations of and attitudes towards English learning also became an obstacle.     

Globalization and the freedom of knowledge

This article considers the transmission of knowledge in higher education. It takes the metaphor of the music industry that pre‐selects the music people can buy. The sales potential is the leading principle in the selection process. Often the small producer is excluded because his or her music is not of commercial interest. The end‐customer does not know what he or she is missing because he or she has never heard the music. It is to be feared that a similar market principle will also influence the selection of knowledge and affect the capacity of higher education institutions to freely generate and transmit new knowledge. The globalization of higher education risks homogenizing the cultural traditions of the non‐Western world through a process of Western cultural domination. On the other hand, the Internet, via open source software like LINUX, might serve to democratize higher education and allow greater grassroots input.     

The cooking teacher: investigating gender stereotypes in a Korean kindergarten

This article discusses some findings from a small‐scale investigation of children's gendered beliefs and behaviours in a Korean kindergarten which was attempting to challenge gender stereotyping through the anti‐bias intervention of a ‘cooking curriculum’. A sample of 14 children, some with ‘working’ mothers and some with ‘housewife’ mothers, was observed for two months, and informally interviewed on several occasions. The children's mothers were also interviewed. The findings are situated in the context of the changing, but still traditional, culture of Korean society, as well as in the contexts of early childhood education and theories of gender acquisition. They confirm that, although children are highly likely to reproduce the beliefs current in their home environment, they are open to reconstructing these views when actively challenged to consider alternatives, either by the school curriculum or by engaging in debate with a researcher or practitioner. The nature of the ‘alternative’ views available may however be problematic.     

政府对高等教育宏观调控的理论与实践研究

研究转型问题 ,首先要搞清楚政府应当如何管理高等教育以及目前政府对高等教育的管理状况。而整个问题的逻辑起点是政府为什么要管理高等教育。基于上述认识 ,本文分析了教育产品的性质和教育公平等问题 ,初步明确了政府管理高等教育的目的 ,进而界定出高等教育中政府和市场的关系。     

Perception of sign language and its application to visual communications for deaf people

Video communication systems for deaf people are limited in terms of quality and performance. Analysis of visual attention mechanisms for sign language may enable optimization of video coding systems for deaf users. Eye-movement tracking experiments were conducted with profoundly deaf volunteers while watching sign language video clips. Deaf people are found to fixate mostly on the facial region of the signer to pick up small detailed movements associated with facial expression and mouth shapes. Lower resolution, peripheral vision is used to process information from larger, rapid movements of the signer in the video clips. A coding scheme that gives priority to the face of the signer may be applied to improve perception of video quality for sign language communication.     

Conflict, Social Competence, and Gender: Maternal and Peer Contexts

The current study was designed to address two major purposes. The first goal was to investigate the joint influence of children's sociometric status and sex on their conflict behavior, and the second goal was to explore the similarities and differences in children's conflict behavior across two contexts, specifically conflicts arising during interactions with mothers and with peers. Forty-two first-graders were videotaped playing with their mothers and then with an unfamiliar peer partner. Conflict behavior occurring in the mother-child context was quite different from that occurring between children, reflecting the contrast between the vertical and horizontal nature of these relationships. Most striking were the large number of sociometric status and sex differences in conflict behavior found across both contexts. Further, it appears that effective conflict behavior may differ for boys and girls. Implications for future research are discussed.     

Intellectual Disability and Developmental Risk: Promoting Intervention to Improve Child and Family Well‐Being

Initial intervention processes for children with intellectual disabilities (IDs) largely focused on direct efforts to impact core cognitive and academic deficits associated with the diagnosis. Recent research on risk processes in families of children with ID, however, has influenced new developmental system approaches to early intervention. Recent risk and resilience processes are reviewed that connect stress, family process, and the high rates of behavioral problems in children with ID that have substantial influence on child and family outcomes. These models are linked to emerging evidence‐based intervention processes that focus on strategic parent skill training and mindfulness interventions that reduce parental stress and create indirect benefits for children's behavioral competencies. A family‐focused developmental systems approach (M. J. Guralnick, 2011) is emphasized.     

Beyond Access: Psychosocial Barriers to Computer Literacy

Research consistently indicates that Latinos and African-Americans are less likely to own and use computers than either Caucasians or Asians. While conventional wisdom holds that high computer costs and lack of access are the primary reasons for this discrepancy, my ethnographic research with 100 low-income adults reveals three non-cost-related psychosocial obstacles that significantly undermine motivation for acquiring computer skills: “relevance,” “fear,” and “self-concept.” My research thus suggests that a more complex relationship exists between ethnicity, identity, and attitudes associated with computers than previously examined; this relationship may better explain why some people are choosing not to use computers at this time. My research also indicates that while community technology centers (CTCs) play an important role in helping adults overcome their resistances and achieve computer literacy, they are presently an underutilized resource—less than 5% of San Diegans use them to meet their computing needs. Hence, my research also questions why more residents do not avail themselves of these community resources. I conclude that efforts to increase computer literacy in underserved communities must go beyond physical access and connectivity and consider the role of cultural factors.