k=0 (−1)n−k ck(T ) λk . Then, as well known, c0(T ) = 0 and c1(T ) = n . If T differs from the star (Sn) and the path (Pn), which requires n ≥ 5 , then c2(Sn) < c2(T ) < c2(Pn) and c3(Sn) < c3(T ) < c3(Pn) . If n = 4 , then c3(Sn) = c3(Pn) . AMS Mathematics Subject Classification (2000): 05C05, 05C12, 05C50

The algebra Sn of one-sided inverses of a polynomial algebra Pn in n variables is obtained from Pn by adding commuting, left (but not two-sided) inverses of the canonical generators of the algebra Pn. Ignoring non-Noetherian property, the algebra Sn belongs to a family of algebras like the nth Weyl algebra An and the polynomial algebra P2n. Explicit generators are found for the group Gn of auto...

حدود ۸۰% از حمل‌ونقل جهانی در بستر دریا انجام می‌شود؛ بنابراین، به‌منظور حفظ ایمنی عبورومرور کشتی‌ها، پیش‌بینی دقیق حرکت آنها اهمیت ویژه‌ای دارد. ازآن‌جاکه پارامترهای زمینه‌ای گوناگونی کشتی‌ها تأثیر می‌گذارد، یکی چالش‌های اصلی حوزة محاسبات زمینه‌ـ آگاه شناسایی بهینة مؤثر کشتی است که ضرورت تحقیق حاضر را می‌رساند. این راستا، با استفاده شبکة عصبی حافظة طولانی کوتاه‌ـ مدت و انتخاب پارامتر به‌شیوة پ...

OBJECTIVE To present the perioperative outcomes from the British Association of Urological Surgeons (BAUS) nephrectomy dataset for 2012, the first year of public reporting of individual surgeon outcomes in the UK. PATIENTS AND METHODS All nephrectomies performed in the year 2012 and recorded in the database were analysed. These were divided into simple nephrectomy (SN), partial nephrectomy (P...

The algebra Sn of one-sided inverses of a polynomial algebra Pn in n variables is obtained from Pn by adding commuting, left (but not two-sided) inverses of the canonical generators of the algebra Pn. The algebra Sn is a noncommutative, non-Noetherian algebra of classical Krull dimension 2n and of global dimension n and is not a domain. If the ground field K has characteristic zero then the alg...

Geometric spreading of Pn and Sn waves in a spherical Earth model is different than that of classical headwaves and is frequency dependent. The behavior cannot be fully represented by a frequency-independent power-law model, as is commonly assumed. The lack of an accurate representation of Pn and Sn geometric spreading in a spherical Earth model impedes our ability to characterize Earth propert...

We study the singular part of the partition monoid Pn; that is, the ideal Pn \ Sn, where Sn is the symmetric group. Our main results are presentations in terms of generators and relations, and we also show that Pn \Sn is idempotent generated, and that its rank and idempotent-rank are both equal to ( n+1 2 ) = 12n(n + 1). One of our presentations uses an idempotent generating set of this minimal...

هدف: کارآفرینی یکی از عوامل کلیدی در توسعه اقتصادی و شاخص اساسی جوامع روبه‌رشد است. آنچه که کارآفرین را به آغاز فعالیت ترغیب می‌کند، انگیزه فرایند تبدیل یک فرد عادی است می‌تواند فرصت‌هایی ایجاد کند حداکثر رساندن ثروت کمک کند. هدف این پژوهش شناسایی طبقه‌بندی انگیزه‌های کارآفرینان می­باشد.طراحی/ روش‌شناسی/ رویکرد: با رویکرد مرور نظام­مند استفاده ماتریس شش سلولی دو مؤلفه جهت (کشش یا فشار) منبع (اق...