sympy/sympy — pull request #2869 by SDB1323 (2014-02-03 13:15:12+00:00)
Title: Added support for Equivalent with multiple arguments in functions

While Equivalent class allows multiple (more than 2) arguments, the supporting functions don't.

1. eliminate_implications gives a wrong answer
pl_true(eliminate_implications(Equivalent(a, b, c)), {a: True, b:False, c:True}) gives True

2. pl_true throws an exception
pl_true(Equivalent(a, b, c), {a: True, b:False, c:True}) gives ValueError: too many values to unpack