ekev (Deut. 7:12) Ramban discusses the interpretations of Targum Onkelos, and of the commentators Rashi and R' A. ibn Ezra and concludes that the word means a roundabout reason or cause, hence the heel which is round is called ekev.

pen tinakesh (Deut. 12:30) Rashi writes:

Onkelos translated this as being an expression of mokesh ('trap'). And I say that he was not concerned with the accurate meaning of the expression, for we have not found Nun in the expression mokesh even as part of the root which drops off, but as an expression of tearing and knocking we have found it with Nun an in 'and his knees knocking on each other' (Daniel 5:6). So here too I say pen tinakesh acharehem, in case you are caught up with them and become close to their deeds.

hayishchem (Deut. 13:4) ('do you have') This is the word yesh with the suffix -chem. This suffix always becomes the stressed syllable of the word to which it is attached. As a result the yesh- part of the word becomes unstressed and being a closed unstressed syllable a short vowel becomes appropriate. (One of the basic rules of vocalization is that a syllable, which is both closed - having a consonant at the end - and unaccented, receives one of the five short vowels Patach, Segol, Chirik, Kubutz, and Kamatz katan.) Indeed instead of the long vowel Tsere we now find the short vowel Chirik. This change is similar to that which occurs in Yissachar which is a combination of yesh-sachar ('there is reward'). Leah regarded the birth of Yissachar as a reward (Gen. 30:18 and Radak there).

Which root theory is followed?

hatishkach isha ulah (Isaiah 49:15) ('would a woman forget her young child?') In context it would be hard to find any other meaning for ulah. Indeed, Yonatan, Rashi, R' A. ibn Ezra, Radak, R' Yosef Kara (the 1st), all interpret it to mean 'her young child.' Nevertheless there is a question. Does this word occur elsewhere in the Tenach? The Masorah annotates ulah with a Lamed, an abbreviation for let ('there is none'). This means that there is no other occurrence of this word in exactly this form in the Tenach (Menachem Cohen ed. Mikra'ot Gedolot 'Haketer' Isaiah, Bar Ilan University, 1996, Masorah p. 12). But is ulah related to any other word in the Tenach? Rashi and R' Yosef Kara refer to the word olal (Jer. 6:11) spelled Ayin Vav Lamed Lamed. R' A. ibn Ezra refers to both olal and to ul (Isaiah 65:20) spelled Ayin Vav Lamed. Radak refers only to ul. Which root theories are indicated by these comments?

Rashi, who wrote before the three-letter root theory had become fully accepted, could relate words that later became regarded as having an Ayin Vav Lamed (Nachei Ayin"Vav) root and words having an Ayin Lamed Lamed (Kefulim) root as belonging to the same two-letter root. This is in line with Menachem, who in his Machberet, lists both olal and ul as belonging to the fifth meaning of the two-letter root Ayin Lamed. (Rashi frequently follows Menachem.) Radak, who sees the root as being Ayin Vav Lamed, is consistent with the later accepted three-letter root theory. It should be noted that although Radak quotes Menachem occasionally I have not been able to find a quotation in connection with the two-letter root theory. It would seem that as far as Radak was concerned the two-letter root theory had been superseded. The views of R' A. ibn Ezra and R' Yosef Kara require further study. R' A. ibn Ezra rarely quotes Menachem and seems also not to raise the two-letter root theory; R' Yosef Kara is not on the Chalamish program so I can't check.

It should be remembered that in 1854 (Yes!) the mathematician and Hebrew scholar, Tzvi (Hirschel) Filipowsky, published the Machberet of Menachem ben Saruk from five manuscripts found in major European libraries, in the hope that it would revive interest in the older theory. Did R' Eliyahu, the Gaon of Vilna (1720-1797), ever see a copy of Machberet Menachem?