elements              package:relations              R Documentation

_E_l_e_m_e_n_t_s _o_f _R_e_l_a_t_i_o_n _D_o_m_a_i_n_s

_D_e_s_c_r_i_p_t_i_o_n:

     Obtain elements of endorelation domains which have certain
     properties.

_U_s_a_g_e:

     relation_elements(x, which, ...)

_A_r_g_u_m_e_n_t_s:

       x: an endorelation.

   which: a character string specifying the property to be tested for. 
          Currently, one of '"minimal"', '"first"', '"last"', or
          '"maximal"', or a unique abbreviation thereof.

     ...: additional arguments to be employed in the property tests.

_D_e_t_a_i_l_s:

     Let R be an endorelation with domain (X, X) and consider elements
     x and y of X.  We say that x is

     _m_i_n_i_m_a_l: there is no y != x with y R x.

     _a _f_i_r_s_t _e_l_e_m_e_n_t: x R y for all y != x.

     _a _l_a_s_t _e_l_e_m_e_n_t: y R x for all y != x.

     _m_a_x_i_m_a_l: there is no y != x with x R y.

     When computing the tests for the above properties, an additional
     'na.rm' argument can be given to control the handling of missing
     incidences.  By default, these are treated as false, to the effect
     that they invalidate for all tests (corresponding to 'na.rm =
     FALSE') and pass the there is no tests (corresponding to 'na.rm
     = TRUE').

_V_a_l_u_e:

     A set with the elements having the specified property.

