Describe the law relating to presumption laid down in section 113A, 113B and 114A of the Indian evidence Act 1872.

Presumptions have played an important place in evidence law, presumption means that the court accepts the existence of any fact. 

Presumptions can be classified into certain categories:
Presumptions of fact.
Presumptions of law.
Mixed Presumptions.

Presumptions of fact are those inferences which are naturally and logically derived based on experience and observations
Presumptions of law are those inferences that are said to be established by law. 
Mixed Presumptions are certain inferences which can be considered as observations of law due to their strength or importance. 

Section 113-A: Presumption as to abetment of suicide by a married woman — When the question is whether the commission of suicide by a woman had been abetted by her husband or any relative of her husband and it is shown that she had committed suicide within seven years from the date of her marriage and that her husband or such relative of her husband had subjected her to cruelty, the court may presume, having regard to all the other circumstances of the case, that such suicide had been abetted by her husband or by such relative of her husband.

Thus Section 113 A provides that when a married women 

(a)    During 7 years from the date of marriage
(b)    Commits suicide 
(c)    And cruelty has been proved by her husband or relative of husband 
Then the court may presume abatement to commit suicide. 
In such circumstances, the burden is on the husband to prove his innocence. 

Section 113B in The Indian Evidence Act, 1872

Presumption as to dowry death.—When the question is whether a person has committed the dowry death of a woman and it is shown that soon before her death such woman has been subjected by such person to cruelty or harassment for, or in connection with, any demand for dowry, the Court shall presume that such person had caused the dowry death.
Thus, Section 113B provides that when there is involved a question of dowry death of a woman and the evidence comes that 
(a)    Before such death was women was subject to cruelty because of demand of dowry 
(b)    She was harassed then the court shall presume that such person committed dowry death. 

The words Soon before death are very important in this section 

Section 114A in The Indian Evidence Act, 1872

Presumption as to absence of consent in certain prosecutions for rape Where sexual intercourse by the accused is proved and the question is whether it was without the consent of the woman alleged to have been raped and she states in her evidence before the Court that she did not consent, the Court shall presume that she did not consent.
Section 114B of the Indian Evidence Act deals with the principles of presumption related to the abetment of suicide to married women for dowry.
But a thin line difference between Section 113A & 114B is that the presumption of Section 114B only comes to the picture if the prosecution has certain proofs that the cause of death was cruelty or maltreatment or harassment for dowry demand. Hence, under this Section, the presumption is carried only when the prosecution proves the case.