Avoiding maximal parabolic subgroups of S_k

We find an explicit expression for the generating function of the number of permutations in S_n avoiding a subgroup of S_k generated by all but one simple transpositions. The generating function turns out to be rational, and its denominator is a rook polynomial for a rectangular board

Perspektif Baru Pengajaran Bahasa Inggris Melalui Direct Method: Sebuah Kajian Kritis

: Lecturers and teachers should be creative in choosing and determining an ap­pro­priate method or approach to be applied in their teaching and learning. The acti­vi­ty of choosing and determining any technique, method, approach, model, and strategy is such a main activity before coming to the class. The fallacy of choosing method in teaching can be a paradoct to the instructional objectives. This the­oretical anlaysis try to reunlock any new perspective of using direct method in con­ducting English teaching and learning process. The way of interpretation and ma­nipulation of method appropriately not only can enhance the quality of tea­ching and learning process but also leaning outcome or students\u27 achievement. Using direct method in teaching English, especially for teaching language skills, such as speaking, grammar aspect, not only in spoken aspect but also written one. Applying direct method in teaching and learning English should pay attention to the students and the characteristics of the materials that will be taught. The using of direct method should be continuously used in teaching and learning English as a foreign language or target language

Cluster algebras and Weil-Petersson forms

In our previous paper we have discussed Poisson properties of cluster algebras of geometric type for the case of a nondegenerate matrix of transition exponents. In this paper we consider the case of a general matrix of transition exponents. Our leading idea that a relevant geometric object in this case is a certain closed 2-form compatible with the cluster algebra structure. The main example is provided by Penner coordinates on the decorated Teichmueller space, in which case the above form coincides with the classic Weil-Petersson symplectic form.Comment: 17 pages, 7 figures; Substantial changes: new proof of Theorem 3.3. Corrected formulation and new proof of Theorem 3.4. Some other minor changes as wel

Generalized cluster structure on the Drinfeld double of GLnGL_n

We construct a generalized cluster structure compatible with the Poisson bracket on the Drinfeld double of the standard Poisson-Lie group $GL_n$ and derive from it a generalized cluster structure on $GL_n$ compatible with the push-forward of the dual Poisson--Lie bracket.Comment: This is a short announcement. The proofs will be published in a subsequent paper. Version 2: several misprints are correcte

FOSTERING STUDENTS’ READING COMPREHENSION OF NARRATIVE TEXT THROUGH GROUP WORK TECHNIQUE

Investigation related to reading comprehension has been conducted by a number of researchers and even some of them focussing their research on reading conprehension of narrative text. However, research on this respect needs pay more attention to be scrutinied. The aims of this research are to know and to describe the implementation of group work technique that improve students reading comprehension of narrative text. The problem raised in the research is about low scores of reading comprehension of narrative text gotten by eighth grade students of SMPN 13 Tangerang Selatan. The number of students is 40. Instrument used in this research is observation, questionnaire, and test. The technique is used in collecting data in the research is qualitative data. The qualitative data consisted of observation within the physical activity in the classroom. Moreover, the questionnaire for student is made to support in collecting the data. In analyzing qualitative data, rating scale table is used to measure the observation of students’ activities during teaching learning process. Meanwhile, some statistical formula is used in analyzing the numerical data. The findings of this study are: 1. Related to the test result, there are 20% or 8 students passing KKM in pre action test, 47.5% or 21 students passing KKM in cycle 1 test and 80% or 32 students passing KKM in cycle 2. 2. Related to the observation result, the students were more active and interested in learning reading activity in the classroom through group work technique. Furthermore, they could cooperative well with their group. It could be known that the students’ reading comprehension in term of narrative text has been improved and teacher was helped in finding the appropriate strategy in teaching reading narrative tex