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Definition df-tru 1310
Description: Definition of  T., a tautology.  T. is a constant true. In this definition biid 227 is used as an antecedent, however, any true wff, such as an axiom, can be used in its place. (Contributed by Anthony Hart, 13-Oct-2010.)
Assertion
Ref Expression
df-tru  |-  (  T.  <->  (
ph 
<-> 
ph ) )

Detailed syntax breakdown of Definition df-tru
StepHypRef Expression
1 wtru 1307 . 2  wff  T.
2 wph . . 3  wff  ph
32, 2wb 176 . 2  wff  ( ph  <->  ph )
41, 3wb 176 1  wff  (  T.  <->  (
ph 
<-> 
ph ) )
Colors of variables: wff set class
This definition is referenced by:  tru  1312  altdftru  25051  uunT1  28869
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