Schnirelman’s constant is defined as a natural number C such that every natural number n≥2 can be expressed as a sum of at most C primes. In 1930 or so, Schnirelman, using the density method set up by himself, prove...Schnirelman’s constant is defined as a natural number C such that every natural number n≥2 can be expressed as a sum of at most C primes. In 1930 or so, Schnirelman, using the density method set up by himself, proved the existence of C. Since then, many researchers have been interested in finding the exact value of C (in virtue of the well-known Goldbaeh conjecture, the value should be 3). The most important progress so far was made by R. C. Vaughan in 1977. Using the improved large sieve with weights and the density method, he proved that C≤27. In 1981, Ding展开更多
In a recent paper of R. Alexander’s a conjecture is proposed as follows: Suppose two n-simplices have vertices P1, P2, …, Pn+1 and P′1, P′2, …, P′n+1 respectively, a new simplex p″1, p″2, …, p″n+1 is made such
文摘中学英语课本中有不少短语,既可按构成特点进行解剖理解并使用,称为自由式短语(free phrase)(此时往往是字面意思),又可从固定搭配即习语(idion)的角度来理解并使用(此时往往是其引申含义),其词性和语法功能有时有较大差别。现举数例分析如下,以备学习时借鉴。 1.as good as①和……一样好(自由式短语);②和……
文摘Schnirelman’s constant is defined as a natural number C such that every natural number n≥2 can be expressed as a sum of at most C primes. In 1930 or so, Schnirelman, using the density method set up by himself, proved the existence of C. Since then, many researchers have been interested in finding the exact value of C (in virtue of the well-known Goldbaeh conjecture, the value should be 3). The most important progress so far was made by R. C. Vaughan in 1977. Using the improved large sieve with weights and the density method, he proved that C≤27. In 1981, Ding
文摘In a recent paper of R. Alexander’s a conjecture is proposed as follows: Suppose two n-simplices have vertices P1, P2, …, Pn+1 and P′1, P′2, …, P′n+1 respectively, a new simplex p″1, p″2, …, p″n+1 is made such
