
Researcher:   In completing the argument table (3
rd
 
row of the  2
nd
 column),  you  only  use 
properties  
    , but  not  yet 
using  properties 
  ,  why 
not use properties 
? 
M
Eks-16
:   I  see  in  the  example  only  properties 
  , written by Sir 
Researcher:   Oh  yes,  but as soon as  you complete 
the  next  column,  there  appear 
properties 
,  what 
underlies you write like that? 
M
Eks-16
:   When  I  write  like  that,  I  think   
with  can share one another, Sir 
Researcher:   If you look at the time you compile a 
formal proof, election    it's right, 
but  once  compiling  the  next  step 
appears 
 
  ,  this  step 
is illogical, why do this? 
M
Eks-16
:   After I tried using it … I mean what I 
fill in the table of informal arguments, 
I think this is correct Sir, it turns out 
this  is  wrong,  sir,  I  have  a  bit  of 
difficulty  utilizing  the  traits
 and manipulate signs of inequality 
sir 
Researcher:   Ok, thank you, I think you have shown 
a  persistent  effort  to  do  proofs, 
hopefully for the next question you are 
better. 
 
From the results of the interview, it shows that 
the  third row  of  the  second column,  students  have 
tried to include the previous pieces of evidence with 
categories and coding, but the pieces of evidence in 
the form of arguments that have not guaranteed the 
next  trait,  students  have  not  used  the  properties  of 
.  Then  for  the  next  column,  students 
have  used  the  previous  step,  but  the  pieces  of 
evidence  for  the  choice  assumption  category  (AC) 
and (DEF) are ”   
 
”  
becomes illogical, even though in the selection δ = ε 
as in the column it shows that the student is right to 
choose.  Next  in  compiling  formal  evidence,  the 
steps in the first row up to the third row of students 
have  done  correctly,  by  using  triangular  inequality 
and properties 
  , but in the fourth row the 
students  repeated,  making  mistakes  entering  “ 
 
”,so  this  formal  proof 
becomes invalid. 
In  general,  from  the  results  of  the  analysis  of 
student  work  for  question  number  1,  several 
obstacles  can  be  found  which  cause  student 
difficulties  in  proving,  as  follows:  (1)  When 
completing  the  informal  argument  table,  students 
cannot yet utilize the general nature of 
  
and 
  , (2) Make mistakes in selection δ and 
manipulate  the  nature  of  inequality  ≤  to  be  < 
(obstacle  to  manipulating  algebraic  forms),  (3) 
Students  have  difficulty  utilizing  the  concepts 
related  to  the  questions  to  be  proven,  and  (4) 
Students  have  difficulty  connecting  informal 
arguments and rewriting them into formal proof. 
4   CONCLUSIONS 
In general, from the results of the analysis of student 
work, several obstacles can be found which give rise 
to  student  difficulties  in  proof,  namely  when 
completing  the  informal  argument  table,  students 
were not able to take advantage of the general nature 
of |cos x | ≤ 1, making mistakes in the selection δ do 
proof construction into formal proof, manipulate the 
nature  of  inequality  ≤  to  be  (obstacle  to 
manipulating  algebraic  forms),  students  have 
difficulty utilizing concepts related to the questions 
to  be  proven,  students  have  difficulty  connecting 
informal arguments and rewriting them into formal 
proof,  and  in  the  final  settlement  in  constructing 
proofs  of  students  experiencing  obstacles  in  using 
the previous steps to formulate formal proof. 
REFERENCES 
Brousseau,  G.  1997.  Theory  of  didactical  situations  in 
mathematics. Dordrecht: Kluwer academic publisher. 
Cornu,  B.  1991.  Limits.  In  D.  Tall  (Ed.),  Advanced 
mathematical  thinking.  (pp.  153-166).  Dordrecht: 
Kluwer Academic Publishers. 
Dubinsky,  E.  1991.  Reflective  abstraction  in  advanced 
mathematical  thinking.  In  D.  Tall  (Ed.),  Advanced 
mathematical  thinking  (pp.  95-126).  Dordrecht: 
Kluwer academic publishers. 
Hanna, G. 1995. Challenges  to the importance of proof. 
For the Learning of Mathematics, 15(3), 42–49. 
Knuth, E. J. 2002. Secondary school mathematics teachers' 
conceptions  of  proof.  Journal  for  Research  in 
Mathematics Education, 33(5):379-405. 
Magajna,  Z.  2013.    Overcoming  the  Obstacle  of  Poor 
Knowledge  in  Proving  Geometry  Tasks,  Journal 
Centre for Educational Policy Studies. 3(4), 99-115. 
Identifying Mathematics Education Studentsâ
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Z Obstacles in Reading and Constructing Proof in Real Analysis Courses
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