The perpetual decline of students’ performance in external geography examinations necessitated this enquiry to identify causes failure reported by examiners. This study, therefore, adopted a qualitative approach analyze West African Examination Council (WAEC) chief examiners’ reports from 2008 2018 extract vital information on why Nigerian students perform poorly geography, using the grounded t...

In recent years, with the regulation of national policy, Chinese real estate market has been rapidly cooling, and real estate enterprises also have difficulties in financing. Perpetual bonds as a historic mezzanine financial instrument abroad was formally introduced into China in 2013 and its own characteristics can satisfy the current needs of the real estate enterprises. This paper analyzes t...

If the costs of going back on previously agreed tari¤ reductions are high relative to the terms of trade gains, then the multilateral liberalization process becomes ‘perpetual’. Perpetual trade liberalization has two unique characteristics. (i) No ‘e¢cient’ tari¤ level exists at which liberalization stops. (ii) Some liberalization must occur in every period. International agreements and institu...

A marked Petri net is lucent if there are no two different reachable markings enabling the same set of transitions, i.e., states are fully characterized by the transitions they enable. This paper explores the class of marked Petri nets that are lucent and proves that perpetual marked free-choice nets are lucent. Perpetual free-choice nets are free-choice Petri nets that are live and bounded and...

Let R be an associative ring in which an identity element is not assumed. A right quotient ring of P is an overring 5 such that for each aQS there corresponds rQR such that arQR and ar 9*0. A theorem of R. E. Johnson [l ] states that R possesses a right quotient ring S which is a (von Neumann) regular ring if and only if P has vanishing right singular ideal. In this case P possesses a unique (u...