51XX 


Geometry {For algebraic geometry, see 14XX} 

51Exx 

Finite geometry and special incidence structures 


51E05 
General block designs [See also 05B05] 


51E10 
Steiner systems 


51E12 
Generalized quadrangles, generalized polygons 


51E14 
Finite partial geometries (general), nets, partial spreads 


51E15 
Affine and projective planes 


51E20 
Combinatorial structures in finite projective spaces [See also 05Bxx] 


51E21 
Blocking sets, ovals, $k$arcs 


51E22 
Linear codes and caps in Galois spaces [See also 94B05] 


51E23 
Spreads and packing problems 


51E24 
Buildings and the geometry of diagrams 


51E25 
Other finite nonlinear geometries 


51E26 
Other finite linear geometries 


51E30 
Other finite incidence structures [See also 05B30] 


51E99 
None of the above, but in this section 