RIGHT_BETA : (thm -> thm)
STRUCTURE
Drule
SYNOPSIS
Beta-reduces a top-level beta-redex on the right-hand side of an equation.
DESCRIPTION
When applied to an equational theorem, RIGHT_BETA applies beta-reduction at top level to the right-hand side (only). Variables are renamed if necessary to avoid free variable capture. 
    A |- s = (\x. t1) t2
   ----------------------  RIGHT_BETA
     A |- s = t1[t2/x]

FAILURE
Fails unless the theorem is equational, with its right-hand side being a top-level beta-redex.
SEEALSO
BETA_CONV, BETA_RULE, BETA_TAC, RIGHT_LIST_BETA
HOL  Kananaskis-14