Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the canonical threefolds with strictly nef anticanonical divisors   Any ample Cartier divisor D on a projective variety X is strictly nef (i.e.
D.C>0 for any effective curve C on X). In general, the converse statement does
not hold. But this is conjectured to be true for anticanonical divisors.
  The present paper establishes this fact for normal complex projective
threefolds with canonical singularities. This result extends several previously
known special cases.
  The proof rests mainly on sophisticated techniques of three dimensional
birational geometry developed in the last two decades.

25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th