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Definition df-tru 1312
Description: Definition of  T., a tautology.  T. is a constant true. In this definition biid 229 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 1309 . 2  wff  T.
2 wph . . 3  wff  ph
32, 2wb 178 . 2  wff  ( ph  <->  ph )
41, 3wb 178 1  wff  (  T.  <->  (
ph 
<-> 
ph ) )
Colors of variables: wff set class
This definition is referenced by:  tru  1314  altdftru  24347  uunT1  27824
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